Migrate from OSSRH to Central Portal (#698)

Ref: https://central.sonatype.org/publish/publish-portal-maven/

Signed-off-by: Pierangelo Di Pilato <pierdipi@redhat.com>

.github/dependabot.yml

@@ -0,0 +1,11 @@
+# To get started with Dependabot version updates, you'll need to specify which
+# package ecosystems to update and where the package manifests are located.
+# Please see the documentation for all configuration options:
+# https://docs.github.com/github/administering-a-repository/configuration-options-for-dependency-updates
+
+version: 2
+updates:
+  - package-ecosystem: "maven"
+    directory: "/" # Location of package manifests
+    schedule:
+      interval: "daily"

.github/workflows/branch.yaml

@@ -4,6 +4,8 @@ on:
   push:
     branches:
       - master
+      - main
+      - '[0-9]+.[0-9]+'
 
 jobs:
   test:
@@ -11,7 +13,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        java: [ 8, 11 ]
+        java: [ 8, 11, 17 ]
     steps:
       - uses: actions/checkout@v2
       - name: Setup java
@@ -19,8 +21,9 @@ jobs:
         with:
           java-version: ${{ matrix.java }}
       - run: |
-          mvn clean install -DskipTests -B
-          mvn verify -B
+          ./mvnw clean install -DskipTests -B
+          ./mvnw verify -B
+
   deploy:
     runs-on: ubuntu-latest
     name: Deploy
@@ -31,13 +34,13 @@ jobs:
         uses: actions/setup-java@v1
         with:
           java-version: 8
-          server-id: ossrh # Value of the distributionManagement/repository/id field of the pom.xml
+          server-id: central # Value of the distributionManagement/repository/id field of the pom.xml
           server-username: MAVEN_USERNAME # env variable for username in deploy
           server-password: MAVEN_CENTRAL_TOKEN # env variable for token in deploy
           gpg-private-key: ${{ secrets.MAVEN_GPG_PRIVATE_KEY }} # Value of the GPG private key to import
           gpg-passphrase: MAVEN_GPG_PASSPHRASE # env variable for GPG private key passphrase
       - name: Publish to Apache Maven Central
-        run: mvn clean deploy -Drelease -DskipTests -B
+        run: ./mvnw clean deploy -Drelease -DskipTests -B
         env:
           MAVEN_USERNAME: ${{ secrets.MAVEN_USERNAME }}
           MAVEN_CENTRAL_TOKEN: ${{ secrets.MAVEN_CENTRAL_TOKEN }}

.github/workflows/bump.yaml

@@ -5,6 +5,14 @@ on:
       version:
         description: 'Version to bump (without prepending "v")'
         required: true
+      maven-modules:
+        description: "Whether to bump versions in pom.xml files"
+        type: choice
+        required: true
+        default: 'true'
+        options:
+          - 'true'
+          - 'false'
 
 jobs:
   bump:
@@ -19,7 +27,8 @@ jobs:
         with:
           java-version: 8
       - name: Bump version using Maven
-        run: 'mvn versions:set -DnewVersion=$NEW_VERSION -DgenerateBackupPoms=false -B'
+        if: ${{ inputs.maven-modules == 'true' }}
+        run: './mvnw versions:set -DnewVersion=$NEW_VERSION -DgenerateBackupPoms=false -B'
       - name: Bump version in docs
         if: ${{ !endsWith(github.event.inputs.version, 'SNAPSHOT') }}
         run: 'find . -type f -name "*.md" -exec sed -i -e "s+<version>[a-zA-Z0-9.-]*<\/version>+<version>$NEW_VERSION</version>+g" {} +'

.github/workflows/pr.yaml

@@ -4,20 +4,24 @@ on:
   pull_request:
     branches:
       - master
+      - main
+      - '[0-9]+.[0-9]+'
 
 jobs:
   test:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        java: [ 8, 11 ]
+        java: [ 8, 11, 17 ]
     name: Java ${{ matrix.java }} Test
     steps:
       - uses: actions/checkout@v2
       - name: Setup java
-        uses: actions/setup-java@v1
+        uses: actions/setup-java@v2
         with:
           java-version: ${{ matrix.java }}
+          distribution: 'temurin'
       - run: |
-          mvn clean install -DskipTests -B
-          mvn verify -B
+          ./mvnw clean install -DskipTests -B
+          ./mvnw verify -B
+          ./mvnw javadoc:javadoc

.gitignore

@@ -42,3 +42,8 @@ _site/
 .sass-cache/
 .jekyll-cache/
 .jekyll-metadata
+
+# MacOS
+*.DS_Store
+/http/restful-ws-jakarta/src/main/*
+

CONTRIBUTING.md

@@ -1,4 +1,19 @@
-# Pull Request Guidelines
+# Contributing to CloudEvents' Java SDK
+
+:+1::tada: First off, thanks for taking the time to contribute! :tada::+1:
+
+We welcome contributions from the community! Please take some time to become
+acquainted with the process before submitting a pull request. There are just
+a few things to keep in mind.
+
+# Pull Requests
+
+Typically, a pull request should relate to an existing issue. If you have
+found a bug, want to add an improvement, or suggest an API change, please
+create an issue before proceeding with a pull request. For very minor changes
+such as typos in the documentation this isn't really necessary.
+
+## Pull Request Guidelines
 
 Here you will find step by step guidance for creating, submitting and updating
 a pull request in this repository. We hope it will help you have an easy time
@@ -8,7 +23,7 @@ your code. Thanks for getting involved! :rocket:
 * [Getting Started](#getting-started)
 * [Branches](#branches)
 * [Commit Messages](#commit-messages)
-* [Staying current with master](#staying-current-with-master)
+* [Staying current with main](#staying-current-with-main)
 * [Submitting and Updating a Pull Request](#submitting-and-updating-a-pull-request)
 * [Congratulations!](#congratulations)
 
@@ -32,7 +47,7 @@ organized.
 
 ```console
 git fetch upstream
-git reset --hard upstream/master
+git reset --hard upstream/main
 git checkout FETCH_HEAD
 git checkout -b 48-fix-http-agent-error
 ```
@@ -87,19 +102,19 @@ Date:   Thu Feb 2 11:41:15 2018 -0800
 Notice the `Author` and `Signed-off-by` lines match. If they don't your PR will
 be rejected by the automated DCO check.
 
-## Staying Current with `master`
+## Staying Current with `main`
 
-As you are working on your branch, changes may happen on `master`. Before
+As you are working on your branch, changes may happen on `main`. Before
 submitting your pull request, be sure that your branch has been updated
 with the latest commits.
 
 ```console
 git fetch upstream
-git rebase upstream/master
+git rebase upstream/main
 ```
 
 This may cause conflicts if the files you are changing on your branch are
-also changed on master. Error messages from `git` will indicate if conflicts
+also changed on main. Error messages from `git` will indicate if conflicts
 exist and what files need attention. Resolve the conflicts in each file, then
 continue with the rebase with `git rebase --continue`.
 
@@ -116,15 +131,15 @@ git push -f origin 48-fix-http-agent-error
 Before submitting a pull request, you should make sure that all of the tests
 successfully pass.
 
-Once you have sent your pull request, `master` may continue to evolve
-before your pull request has landed. If there are any commits on `master`
+Once you have sent your pull request, `main` may continue to evolve
+before your pull request has landed. If there are any commits on `main`
 that conflict with your changes, you may need to update your branch with
 these changes before the pull request can land. Resolve conflicts the same
 way as before.
 
 ```console
 git fetch upstream
-git rebase upstream/master
+git rebase upstream/main
 # fix any potential conflicts
 git push -f origin 48-fix-http-agent-error
 ```
@@ -141,7 +156,7 @@ for details.
 
 ```console
 git commit -m "fixup: fix typo"
-git rebase -i upstream/master # follow git instructions
+git rebase -i upstream/main # follow git instructions
 ```
 
 Once you have rebased your commits, you can force push to your fork as before.

MAINTAINERS.md

@@ -0,0 +1,5 @@
+# Maintainers
+
+Current active maintainers of this SDK:
+
+- [Pierangelo Di Pilato](https://github.com/pierDipi)

MAINTAINERS_GUIDE.md

@@ -1,17 +1,5 @@
 # Maintainer's Guide
 
-## Release Process
-
-The release process is automated with Github actions. In order to perform a release:
-
-1. Check if master CI pass.
-1. Open the Github repository main page and go in the tab "Actions". Trigger the workflow "Bump version" and insert the new version to release. This will create a new release PR.
-1. Check the release PR, merge it and cleanup the created branch.
-1. Wait for the CI to complete the deploy of the modules to OSSRH.
-1. Using the Github UI, create a new release, specifying the release notes and the tag to use.
-1. Trigger again the workflow "Bump version" to bump versions back to a snapshot version.
-1. Check the snapshot release PR, merge it and cleanup the created branch.
-
 ## Tips
 
 Here are a few tips for repository maintainers.
@@ -38,14 +26,14 @@ When landing pull requests, be sure to check the first line uses an appropriate
 
 ## Branch Management
 
-The `master` branch is the bleeding edge. New major versions of the module
+The `main` branch is the bleeding edge. New major versions of the module
 are cut from this branch and tagged. If you intend to submit a pull request
-you should use `master HEAD` as your starting point.
+you should use `main HEAD` as your starting point.
 
 Each major release will result in a new branch and tag. For example, the
 release of version 1.0.0 of the module will result in a `v1.0.0` tag on the
 release commit, and a new branch `v1.x.y` for subsequent minor and patch
 level releases of that major version. However, development will continue
-apace on `master` for the next major version - e.g. 2.0.0. Version branches
+apace on `main` for the next major version - e.g. 2.0.0. Version branches
 are only created for each major version. Minor and patch level releases
 are simply tagged.

README.md

@@ -4,10 +4,20 @@
 [![Maven Central](https://maven-badges.herokuapp.com/maven-central/io.cloudevents/cloudevents-parent/badge.svg)](https://maven-badges.herokuapp.com/maven-central/io.cloudevents/cloudevents-parent)
 [![Javadocs](http://www.javadoc.io/badge/io.cloudevents/cloudevents-core.svg?color=green)](http://www.javadoc.io/doc/io.cloudevents/cloudevents-core)
 
-A Java API for the
-[CloudEvents specification](https://github.com/cloudevents/spec)
+The Java SDK for CloudEvents is a collection of Java packages to adopt
+[CloudEvents](https://github.com/cloudevents/spec) in your Java application.
 
-Look at https://cloudevents.github.io/sdk-java/ for more documentation.
+Using the Java SDK you can:
+
+-   Access, create and manipulate `CloudEvent` inside your application.
+-   Serialize and deserialize `CloudEvent` back and forth using the _CloudEvents
+    Event Format_, like Json.
+-   Read and write `CloudEvent` back and forth to HTTP, Kafka, AMQP using the
+    _CloudEvents Protocol Binding_ implementations we provide for a wide range
+    of well known Java frameworks/libraries.
+
+To check out the complete documentation and how to get started, look at the dedicated website
+https://cloudevents.github.io/sdk-java/.
 
 ## Status
 
@@ -32,46 +42,45 @@ Supported features of the specification:
 |         - [Vert.x](http/vertx)          |                  :heavy_check_mark:                   |                  :heavy_check_mark:                   |
 | - [Jakarta Restful WS](http/restful-ws) |                  :heavy_check_mark:                   |                  :heavy_check_mark:                   |
 |          - [Basic](http/basic)          |                  :heavy_check_mark:                   |                  :heavy_check_mark:                   |
+|           - [Spring](spring)            |                  :heavy_check_mark:                   |                  :heavy_check_mark:                   |
+|           - [http4k][http4k]<sup>†</sup>|                  :heavy_check_mark:                   |                  :heavy_check_mark:                   |
 |            JSON Event Format            |                  :heavy_check_mark:                   |                  :heavy_check_mark:                   |
 |    - [Jackson](formats/json-jackson)    |                  :heavy_check_mark:                   |                  :heavy_check_mark:                   |
+|            Protobuf Event Format        |                  :heavy_check_mark:                   |                  :heavy_check_mark:                   |
+|            - [Proto](formats/protobuf)  |                  :heavy_check_mark:                   |                  :heavy_check_mark:                   |
 |     [Kafka Protocol Binding](kafka)     |                  :heavy_check_mark:                   |                  :heavy_check_mark:                   |
 |          MQTT Protocol Binding          |                          :x:                          |                          :x:                          |
 |          NATS Protocol Binding          |                          :x:                          |                          :x:                          |
 |                Web hook                 |                          :x:                          |                          :x:                          |
 
-## Motivation
-
-The [CloudEvents specification](https://github.com/cloudevents/spec) is a
-vendor-neutral specification for defining the format of event data that is being
-exchanged between different cloud systems. The specification basically defines
-an abstract envelope for any event data payload, without knowing specific
-implementation details of the actual underlying event. The current version of
-the spec is at `1.0` and it describes a simple event format, which was
-demonstrated at [KubeCon 2018](https://youtu.be/TZPPjAv12KU) using different
-_Serverless platforms_, such as
-[Apache Openwhisk](https://github.com/apache/incubator-openwhisk).
+<sub>† Source/artifacts hosted externally</sub>
 
 ## Documentation
 
-Documentation is available at https://cloudevents.github.io/sdk-java/
+Documentation is available at https://cloudevents.github.io/sdk-java/.
 
 Javadocs are available on [javadoc.io](https://www.javadoc.io):
 
 -   [cloudevents-api](https://www.javadoc.io/doc/io.cloudevents/cloudevents-api)
 -   [cloudevents-core](https://www.javadoc.io/doc/io.cloudevents/cloudevents-core)
+-   [cloudevents-avro-compact](https://www.javadoc.io/doc/io.cloudevents/cloudevents-avro-compact)
 -   [cloudevents-json-jackson](https://www.javadoc.io/doc/io.cloudevents/cloudevents-json-jackson)
+-   [cloudevents-protobuf](https://www.javadoc.io/doc/io.cloudevents/cloudevents-protobuf)
+-   [cloudevents-xml](https://www.javadoc.io/doc/io.cloudevents/cloudevents-xml)
 -   [cloudevents-http-basic](https://www.javadoc.io/doc/io.cloudevents/cloudevents-http-basic)
 -   [cloudevents-http-restful-ws](https://www.javadoc.io/doc/io.cloudevents/cloudevents-http-restful-ws)
 -   [cloudevents-http-vertx](https://www.javadoc.io/doc/io.cloudevents/cloudevents-http-vertx)
 -   [cloudevents-kafka](https://www.javadoc.io/doc/io.cloudevents/cloudevents-kafka)
+-   [cloudevents-amqp](https://www.javadoc.io/doc/io.cloudevents/cloudevents-amqp)
+-   [cloudevents-spring](https://www.javadoc.io/doc/io.cloudevents/cloudevents-spring)
 
 You can check out the examples in the [examples](examples) directory.
 
 ## Used By
 
-| [Occurrent](https://occurrent.org)                                                                                                                                                                                                              | [Knative Eventing](https://github.com/knative-sandbox/eventing-kafka-broker)                                                                                   |
-| ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------- |
-| <a href="https://occurrent.org"><img src="https://raw.githubusercontent.com/johanhaleby/occurrent/master/occurrent-logo-196x196.png" width="98" height="98" alt="Occurrent" title="Occurrent - Event Sourcing Utilities for the JVM"></img></a> | <a href="https://github.com/knative-sandbox/eventing-kafka-broker"><img src="https://cloudevents.io/img/logos/integrations/knative.png" height="98"></img></a> |
+| [Occurrent](https://occurrent.org) | [Knative Eventing](https://github.com/knative-sandbox/eventing-kafka-broker )| [http4k][http4k] |
+| ---------------------------------- | ---------------------------------------------------------------------------- | ---------------|
+| <a href="https://occurrent.org"><img src="https://raw.githubusercontent.com/johanhaleby/occurrent/master/occurrent-logo-196x196.png" width="98" height="98" alt="Occurrent" title="Occurrent - Event Sourcing Utilities for the JVM"></img></a> | <a href="https://github.com/knative-sandbox/eventing-kafka-broker"><img src="https://cloudevents.io/img/logos/integrations/knative.png" height="98"></img></a> | <a href="https://www.http4k.org/guide/modules/cloud_events/"><img src="https://http4k.org/img/favicon-310.png" height="98" alt="http4k" title="http4k"></img></a> | |
 
 ## Community
 
@@ -90,11 +99,25 @@ You can check out the examples in the [examples](examples) directory.
 
 Each SDK may have its own unique processes, tooling and guidelines, common
 governance related material can be found in the
-[CloudEvents `community`](https://github.com/cloudevents/spec/tree/master/community)
+[CloudEvents `community`](https://github.com/cloudevents/spec/tree/main/docs)
 directory. In particular, in there you will find information concerning how SDK
 projects are
-[managed](https://github.com/cloudevents/spec/blob/master/community/SDK-GOVERNANCE.md),
-[guidelines](https://github.com/cloudevents/spec/blob/master/community/SDK-maintainer-guidelines.md)
+[managed](https://github.com/cloudevents/spec/blob/main/docs/SDK-GOVERNANCE.md),
+[guidelines](https://github.com/cloudevents/spec/blob/main/docs/SDK-maintainer-guidelines.md)
 for how PR reviews and approval, and our
-[Code of Conduct](https://github.com/cloudevents/spec/blob/master/community/GOVERNANCE.md#additional-information)
+[Code of Conduct](https://github.com/cloudevents/spec/blob/main/docs/GOVERNANCE.md#additional-information)
 information.
+
+If there is a security concern with one of the CloudEvents specifications, or
+with one of the project's SDKs, please send an email to
+[cncf-cloudevents-security@lists.cncf.io](mailto:cncf-cloudevents-security@lists.cncf.io).
+
+## Additional SDK Resources
+
+- [List of current active maintainers](MAINTAINERS.md)
+- [How to contribute to the project](CONTRIBUTING.md)
+- [SDK's License](LICENSE)
+- [SDK's Release process](RELEASING.md)
+- [SDK Maintainer's guide](MAINTAINERS_GUIDE.md)
+
+[http4k]: https://www.http4k.org/guide/reference/cloud_events/

RELEASING.md

@@ -0,0 +1,12 @@
+# Release Process
+
+The release process is automated with Github actions. In order to perform a release:
+
+1. Check if main CI pass.
+1. Open the Github repository main page and go in the tab "Actions". Trigger the workflow "Bump version" and insert the new version to release. This will create a new release PR.
+1. Check the release PR, merge it and cleanup the created branch.
+1. Wait for the CI to complete the deploy of the modules to OSSRH.
+1. Using the Github UI, create a new release, specifying the release notes and the tag to use.
+1. Trigger again the workflow "Bump version" to bump versions back to a snapshot version.
+1. Check the snapshot release PR, merge it and cleanup the created branch.
+

amqp/README.md

@@ -1,35 +1,5 @@
 # AMQP Protocol Binding
 
-[![Javadocs](http://www.javadoc.io/badge/io.cloudevents/cloudevents-amqp-proton.svg?color=green)](http://www.javadoc.io/doc/io.cloudevents/cloudevents-amqp-proton)
+Javadoc: [![Javadocs](http://www.javadoc.io/badge/io.cloudevents/cloudevents-amqp-proton.svg?color=green)](http://www.javadoc.io/doc/io.cloudevents/cloudevents-amqp-proton)
 
-This module implements `MessageReader` and `MessageWriter` using the Qpid Proton library. It can be used with Qpid Proton or any integrations based on Qpid Proton  (e.g vertx-proton). 
-
-For Maven based projects, use the following to configure the `proton` AMQP binding for CloudEvents:
-
-```xml
-<dependency>
-    <groupId>io.cloudevents</groupId>
-    <artifactId>cloudevents-amqp-proton</artifactId>
-    <version>2.0.0.RC1</version>
-</dependency>
-```
-
-## Sending and Receiving CloudEvents
-
-To send and receive CloudEvents we use `MessageWriter` and `MessageReader`, respectively.
-This module offers factory methods for creation of those in `ProtonAmqpMessageFactory`.
-
-```java
-public class ProtonAmqpMessageFactory {
-    public static MessageReader createReader(final Message message);
-    public static MessageReader createReader(final String contentType, final byte[] payload);
-    public static MessageReader createReader(final String contentType, final ApplicationProperties props, final byte[] payload);
-    public static MessageWriter createWriter();
-}
-```
-
-Examples:
-
-The example uses the vertx-proton integration to send/receive CloudEvent messages over AMQP.
-* [Vertx AmqpServer](../../examples/amqp-proton/src/main/java/io/cloudevents/examples/amqp/vertx/AmqpServer.java)
-* [Vertx AmqpClient](../../examples/amqp-proton/src/main/java/io/cloudevents/examples/amqp/vertx/AmqpClient.java)
+Documentation: https://cloudevents.github.io/sdk-java/amqp-proton

amqp/pom.xml

@@ -6,7 +6,7 @@
 	<parent>
 		<groupId>io.cloudevents</groupId>
 		<artifactId>cloudevents-parent</artifactId>
-		<version>2.0.0-SNAPSHOT</version>
+		<version>4.1.0-SNAPSHOT</version>
 	</parent>
 
 	<artifactId>cloudevents-amqp-proton</artifactId>
@@ -14,10 +14,12 @@
 	<packaging>jar</packaging>
 
     <properties>
-       <protonj.version>0.33.7</protonj.version>
+       <protonj.version>0.34.1</protonj.version>
        <jsr305.version>3.0.2</jsr305.version>
+        <module-name>io.cloudevents.amqp.proton</module-name>
     </properties>
-	<dependencies>
+
+    <dependencies>
 		<dependency>
 			<groupId>org.apache.qpid</groupId>
 			<artifactId>proton-j</artifactId>

amqp/src/main/java/io/cloudevents/amqp/ProtonAmqpMessageFactory.java

@@ -17,7 +17,7 @@
 
 package io.cloudevents.amqp;
 
-
+import io.cloudevents.SpecVersion;
 import io.cloudevents.amqp.impl.AmqpConstants;
 import io.cloudevents.amqp.impl.ProtonAmqpBinaryMessageReader;
 import io.cloudevents.amqp.impl.ProtonAmqpMessageWriter;
@@ -25,13 +25,17 @@ import io.cloudevents.core.message.MessageReader;
 import io.cloudevents.core.message.MessageWriter;
 import io.cloudevents.core.message.impl.GenericStructuredMessageReader;
 import io.cloudevents.core.message.impl.MessageUtils;
+import io.cloudevents.lang.Nullable;
+import io.cloudevents.rw.CloudEventRWException;
 import io.cloudevents.rw.CloudEventWriter;
 import org.apache.qpid.proton.amqp.messaging.ApplicationProperties;
+import org.apache.qpid.proton.amqp.messaging.Section;
 import org.apache.qpid.proton.message.Message;
 
 import javax.annotation.ParametersAreNonnullByDefault;
+
 /**
- * A factory class providing convenience methods for creating MessageReader and MessageWriter instances based on Qpid Proton.
+ * A factory class providing convenience methods for creating {@link MessageReader} and {@link MessageWriter} instances based on Qpid Proton {@link Message}.
  */
 @ParametersAreNonnullByDefault
 public final class ProtonAmqpMessageFactory {
@@ -41,62 +45,47 @@ public final class ProtonAmqpMessageFactory {
     }
 
     /**
-     * Creates a MessageReader to read a proton-based {@link Message}.
-     * <p>
-     * This implementation simply calls {@link #createReader(String, ApplicationProperties, byte[])}.
+     * Creates a {@link MessageReader} to read a proton-based {@link Message}.
+     * This reader is able to read both binary and structured encoded {@link io.cloudevents.CloudEvent}.
      *
-     * @param message The proton message to read from.
-     *
-     * @return        A message reader that can read the given proton message to a cloud event representation.
+     * @param message The proton {@link Message} to read from.
+     * @return A {@link MessageReader} that can read the given proton {@link Message} to a {@link io.cloudevents.CloudEvent} representation.
+     * @throws CloudEventRWException if something goes wrong while resolving the {@link SpecVersion} or if the message has unknown encoding
+     * @see #createReader(String, ApplicationProperties, Section)
      */
-    public static MessageReader createReader(final Message message) {
-
-        final byte[] payload = AmqpConstants.getPayloadAsByteArray(message.getBody());
-        return createReader(message.getContentType(), message.getApplicationProperties(), payload);
+    public static MessageReader createReader(final Message message) throws CloudEventRWException {
+        return createReader(message.getContentType(), message.getApplicationProperties(), message.getBody());
     }
 
     /**
-     * Creates a MessageReader using the content-type property and payload of a proton-based message.
-     * <p>
-     * This method simply calls {@link #createReader(String, ApplicationProperties, byte[])}.
+     * Creates a MessageReader to read using the {@code content-type} property, {@code application-properties} and data payload
+     * of a proton-based {@link Message}. This reader is able to read both binary and structured encoded {@link io.cloudevents.CloudEvent}.
      *
-     * @param contentType The content-type of the message payload.
-     * @param payload     The message payload in bytes.
-     * @return            A message reader capable of representing a CloudEvent from
-     *                    a message <em>content-type</em> property and <em>application-data</em>.
+     * @param contentType The {@code content-type} of the message payload.
+     * @param props       The {@code application-properties} section of the proton-message containing cloud event metadata (attributes and/or extensions).
+     * @param body        The message body or {@code null} if the message does not contain any body.
+     * @return A {@link MessageReader} capable of representing a {@link io.cloudevents.CloudEvent} from the {@code application-properties},
+     * {@code content-type} and payload of a proton message.
+     * @throws CloudEventRWException if something goes wrong while resolving the {@link SpecVersion} or if the message has unknown encoding
      */
-    public static MessageReader createReader(final String contentType, final byte[] payload) {
-        return createReader(contentType, null, payload);
+    public static MessageReader createReader(final String contentType, final ApplicationProperties props, @Nullable final Section body) throws CloudEventRWException {
+        final byte[] payload = AmqpConstants.getPayloadAsByteArray(body);
+        return MessageUtils.parseStructuredOrBinaryMessage(
+            () -> contentType,
+            format -> new GenericStructuredMessageReader(format, payload),
+            () -> AmqpConstants.getApplicationProperty(props, AmqpConstants.APP_PROPERTY_SPEC_VERSION, String.class),
+            sv -> new ProtonAmqpBinaryMessageReader(sv, props, contentType, payload)
+        );
     }
 
     /**
-     * Creates a MessageWriter capable of translating both a structured and binary CloudEvent
-     * to a proton-based AMQP 1.0 representation.
+     * Creates a {@link MessageWriter} capable of translating both a structured and binary CloudEvent
+     * to a proton-based AMQP 1.0 {@link Message}.
      *
-     * @return A message writer to read structured and binary cloud event from a proton-based message.
+     * @return A {@link MessageWriter} to write a {@link io.cloudevents.CloudEvent} to Proton {@link Message} using structured or binary encoding.
      */
     public static MessageWriter<CloudEventWriter<Message>, Message> createWriter() {
         return new ProtonAmqpMessageWriter<>();
     }
 
-    /**
-     * Creates a MessageReader to read using the content-type property, application-propeties and data payload
-     * of a proton-based message.
-     *
-     * @param contentType  The content-type of the message payload.
-     * @param props        The application-properties section of the proton-message containing cloud event metadata (attributes and/or extensions).
-     * @param payload      The message payload in bytes or {@code null} if the message does not contain any payload.
-     * @return             A message reader capable of representing a CloudEvent from the application-properties,
-     *                     content-type and payload of a proton message.
-     */
-    public static MessageReader createReader(final String contentType, final ApplicationProperties props, final byte[] payload) {
-
-        return MessageUtils.parseStructuredOrBinaryMessage(
-                () -> contentType,
-                format -> new GenericStructuredMessageReader(format, payload),
-                () -> AmqpConstants.getApplicationProperty(props, AmqpConstants.APP_PROPERTY_SPEC_VERSION, String.class),
-                sv -> new ProtonAmqpBinaryMessageReader(sv, props, contentType, payload));
-
-    }
-
 }

amqp/src/main/java/io/cloudevents/amqp/impl/ProtonAmqpMessageWriter.java

@@ -17,22 +17,20 @@
 
 package io.cloudevents.amqp.impl;
 
-import java.util.HashMap;
-
-import org.apache.qpid.proton.amqp.Binary;
-import org.apache.qpid.proton.amqp.messaging.ApplicationProperties;
-import org.apache.qpid.proton.amqp.messaging.Data;
-import org.apache.qpid.proton.message.Message;
-
 import io.cloudevents.CloudEventData;
 import io.cloudevents.SpecVersion;
 import io.cloudevents.core.format.EventFormat;
 import io.cloudevents.core.message.MessageWriter;
 import io.cloudevents.core.v1.CloudEventV1;
-import io.cloudevents.rw.CloudEventAttributesWriter;
-import io.cloudevents.rw.CloudEventExtensionsWriter;
+import io.cloudevents.rw.CloudEventContextWriter;
 import io.cloudevents.rw.CloudEventRWException;
 import io.cloudevents.rw.CloudEventWriter;
+import org.apache.qpid.proton.amqp.Binary;
+import org.apache.qpid.proton.amqp.messaging.ApplicationProperties;
+import org.apache.qpid.proton.amqp.messaging.Data;
+import org.apache.qpid.proton.message.Message;
+
+import java.util.HashMap;
 
 /**
  * A proton-based MessageWriter capable of writing both structured and binary CloudEvent messages to an AMQP 1.0 representation as
@@ -53,33 +51,28 @@ public final class ProtonAmqpMessageWriter<R> implements MessageWriter<CloudEven
     }
 
     @Override
-    public CloudEventAttributesWriter withAttribute(final String name, final String value) throws CloudEventRWException {
+    public CloudEventContextWriter withContextAttribute(String name, String value) throws CloudEventRWException {
         if (name.equals(CloudEventV1.DATACONTENTTYPE)) {
             message.setContentType(value);
         } else {
+            // for now, extensions are mapped to application-properties
+            // see https://github.com/cloudevents/sdk-java/issues/30#issuecomment-723982190
             if (applicationProperties == null) {
                 throw new IllegalStateException("This Writer is not initialized");
             }
-            applicationProperties.getValue().put(AmqpConstants.ATTRIBUTES_TO_PROPERTYNAMES.get(name), value);
+            String propName = AmqpConstants.ATTRIBUTES_TO_PROPERTYNAMES.get(name);
+            if (propName == null) {
+                propName = name;
+            }
+            applicationProperties.getValue().put(propName, value);
         }
-        return null;
-    }
-
-    @Override
-    public CloudEventExtensionsWriter withExtension(final String name, final String value) throws CloudEventRWException {
-        // for now, extensions are mapped to application-properties 
-        // see https://github.com/cloudevents/sdk-java/issues/30#issuecomment-723982190
-        if (applicationProperties == null) {
-            throw new IllegalStateException("This Writer is not initialized");
-        }
-        applicationProperties.getValue().put(name, value);
-        return null;
+        return this;
     }
 
     @Override
     public ProtonAmqpMessageWriter<R> create(final SpecVersion version) {
         if (applicationProperties == null) {
-            applicationProperties = new ApplicationProperties(new HashMap<String, Object>());
+            applicationProperties = new ApplicationProperties(new HashMap<>());
         }
         applicationProperties.getValue().put(AmqpConstants.APP_PROPERTY_SPEC_VERSION, version.toString());
         return this;
@@ -105,5 +98,4 @@ public final class ProtonAmqpMessageWriter<R> implements MessageWriter<CloudEven
         message.setApplicationProperties(applicationProperties);
         return message;
     }
-
 }

amqp/src/test/java/io/cloudevents/amqp/ProtonAmqpMessageFactoryTest.java

@@ -17,18 +17,6 @@
 
 package io.cloudevents.amqp;
 
-import static org.assertj.core.api.Assertions.assertThat;
-
-import java.util.AbstractMap.SimpleEntry;
-import java.util.Map;
-import java.util.stream.Collectors;
-import java.util.stream.Stream;
-
-import org.apache.qpid.proton.amqp.messaging.ApplicationProperties;
-import org.junit.jupiter.params.ParameterizedTest;
-import org.junit.jupiter.params.provider.Arguments;
-import org.junit.jupiter.params.provider.MethodSource;
-
 import io.cloudevents.CloudEvent;
 import io.cloudevents.SpecVersion;
 import io.cloudevents.amqp.impl.AmqpConstants;
@@ -39,6 +27,19 @@ import io.cloudevents.core.test.Data;
 import io.cloudevents.core.v03.CloudEventV03;
 import io.cloudevents.core.v1.CloudEventV1;
 import io.cloudevents.types.Time;
+import org.apache.qpid.proton.amqp.Binary;
+import org.apache.qpid.proton.amqp.messaging.ApplicationProperties;
+import org.apache.qpid.proton.amqp.messaging.Section;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.Arguments;
+import org.junit.jupiter.params.provider.MethodSource;
+
+import java.util.AbstractMap.SimpleEntry;
+import java.util.Map;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+import static org.assertj.core.api.Assertions.assertThat;
 
 /**
  * Tests verifying the behavior of the {@code ProtonAmqpMessageFactory}.
@@ -53,7 +54,8 @@ public class ProtonAmqpMessageFactoryTest {
     @MethodSource("binaryTestArguments")
     public void readBinary(final Map<String, Object> props, final String contentType, final byte[] body,
             final CloudEvent event) {
-        final MessageReader amqpReader = ProtonAmqpMessageFactory.createReader(contentType, new ApplicationProperties(props), body);
+        final Section bodySection = body != null ? new org.apache.qpid.proton.amqp.messaging.Data(new Binary(body)) : null;
+        final MessageReader amqpReader = ProtonAmqpMessageFactory.createReader(contentType, new ApplicationProperties(props), bodySection);
         assertThat(amqpReader.getEncoding()).isEqualTo(Encoding.BINARY);
         assertThat(amqpReader.toEvent()).isEqualTo(event);
     }
@@ -64,7 +66,7 @@ public class ProtonAmqpMessageFactoryTest {
         final String contentType = CSVFormat.INSTANCE.serializedContentType() + "; charset=utf8";
         final byte[] contentPayload = CSVFormat.INSTANCE.serialize(event);
 
-        final MessageReader amqpReader = ProtonAmqpMessageFactory.createReader(contentType, null, contentPayload);
+        final MessageReader amqpReader = ProtonAmqpMessageFactory.createReader(contentType, null, new org.apache.qpid.proton.amqp.messaging.Data(new Binary(contentPayload)));
         assertThat(amqpReader.getEncoding()).isEqualTo(Encoding.STRUCTURED);
         assertThat(amqpReader.toEvent()).isEqualTo(event);
     }

api/README.md

@@ -1,28 +1,5 @@
 # CloudEvents API
 
-[![Javadocs](http://www.javadoc.io/badge/io.cloudevents/cloudevents-api.svg?color=green)](http://www.javadoc.io/doc/io.cloudevents/cloudevents-api)
+Javadoc: [![Javadocs](http://www.javadoc.io/badge/io.cloudevents/cloudevents-api.svg?color=green)](http://www.javadoc.io/doc/io.cloudevents/cloudevents-api)
 
-For Maven based projects, use the following dependency:
-
-```xml
-<dependency>
-    <groupId>io.cloudevents</groupId>
-    <artifactId>cloudevents-api</artifactId>
-    <version>2.0.0.RC1</version>
-</dependency>
-```
-
-## Features
-
-This package provides the base interfaces used by the SDK. In particular:
-
-- `CloudEvent` is the main interface representing a read only CloudEvent in-memory representation
-- `Extension` represents a _materialized_ in-memory representation of a CloudEvent extension
-- `SpecVersion` is an enum of CloudEvents' specification versions supported by this SDK version.
-- `CloudEventVisitor`/`CloudEventVisitable` are the interfaces used by the SDK to implement protocol bindings/event formats.
-   A 3rd party implementer can implement these interfaces directly in its `CloudEvent` in order
-   to customize/implement efficiently the marshalling/unmarshalling process.
-   These interfaces are optional and, if your `CloudEvent` doesn't implement it, a default implementation is provided by the SDK.
-
-`cloudevents-core` provides the implementation of these interfaces, and a 3rd party implementer can grab this package
-to implement specialized CloudEvent in-memory representations.
+Documentation: https://cloudevents.github.io/sdk-java/api

api/pom.xml

@@ -24,7 +24,7 @@
     <parent>
         <groupId>io.cloudevents</groupId>
         <artifactId>cloudevents-parent</artifactId>
-        <version>2.0.0-SNAPSHOT</version>
+        <version>4.1.0-SNAPSHOT</version>
     </parent>
 
     <artifactId>cloudevents-api</artifactId>

api/src/main/java/io/cloudevents/CloudEvent.java

@@ -20,12 +20,12 @@ import io.cloudevents.lang.Nullable;
 
 /**
  * Interface representing an in memory read only representation of a CloudEvent,
- * as specified by the <a href="https://github.com/cloudevents/spec/blob/v1.0/spec.md">CloudEvents specification</a>
+ * as specified by the <a href="https://github.com/cloudevents/spec/blob/v1.0/spec.md">CloudEvents specification</a>.
  */
 public interface CloudEvent extends CloudEventContext {
 
     /**
-     * The event data
+     * @return The event data, if any, otherwise {@code null}
      */
     @Nullable
     CloudEventData getData();

api/src/main/java/io/cloudevents/CloudEventExtension.java

@@ -23,10 +23,10 @@ import javax.annotation.ParametersAreNonnullByDefault;
 import java.util.Set;
 
 /**
- * Materialized CloudEvent Extension interface to read/write the extension attributes key/values.
+ * Materialized CloudEvent extension interface to read/write the extension attributes key/values.
  */
 @ParametersAreNonnullByDefault
-public interface Extension {
+public interface CloudEventExtension {
 
     /**
      * Fill this materialized extension with values from a {@link CloudEventExtensions} implementation.
@@ -39,7 +39,7 @@ public interface Extension {
      * Get the attribute of extension named {@code key}.
      *
      * @param key the name of the extension attribute
-     * @return the extension value in one of the valid types String/Number/Boolean
+     * @return the extension value in one of the valid types String/Number/Boolean/URI/OffsetDateTime/byte[]
      * @throws IllegalArgumentException if the key is unknown to this extension
      */
     @Nullable

api/src/main/java/io/cloudevents/SpecVersion.java

@@ -29,11 +29,17 @@ import java.util.stream.Stream;
  */
 @ParametersAreNonnullByDefault
 public enum SpecVersion {
+    /**
+     * @see <a href="https://github.com/cloudevents/spec/releases/tag/v0.3">CloudEvents release v0.3</a>
+     */
     V03(
         "0.3",
         Arrays.asList("specversion", "id", "type", "source"),
         Arrays.asList("datacontenttype", "datacontentencoding", "schemaurl", "subject", "time")
     ),
+    /**
+     * @see <a href="https://github.com/cloudevents/spec/releases/tag/v1.0">CloudEvents release v1.0</a>
+     */
     V1(
         "1.0",
         Arrays.asList("specversion", "id", "type", "source"),

api/src/main/java/io/cloudevents/lang/Nullable.java

@@ -27,6 +27,9 @@ import static java.lang.annotation.ElementType.*;
 import static java.lang.annotation.RetentionPolicy.RUNTIME;
 import static javax.annotation.meta.When.MAYBE;
 
+/**
+ * This annotation is used to define a method parameter or return type as nullable.
+ */
 @Target(value = {METHOD, PARAMETER, FIELD})
 @Retention(value = RUNTIME)
 @Documented

api/src/main/java/io/cloudevents/rw/CloudEventAttributesWriter.java

@@ -1,65 +0,0 @@
-/*
- * Copyright 2018-Present The CloudEvents Authors
- * <p>
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- * <p>
- * http://www.apache.org/licenses/LICENSE-2.0
- * <p>
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- *
- */
-
-package io.cloudevents.rw;
-
-import io.cloudevents.types.Time;
-
-import java.net.URI;
-import java.time.OffsetDateTime;
-
-/**
- * Interface to write the attributes from a {@link io.cloudevents.rw.CloudEventReader} to a new representation.
- */
-public interface CloudEventAttributesWriter {
-
-    /**
-     * Set attribute with type {@link String}. This setter should not be invoked for specversion, because the built Visitor already
-     * has the information through the {@link CloudEventWriterFactory}.
-     *
-     * @param name  name of the attribute
-     * @param value value of the attribute
-     * @return self
-     * @throws CloudEventRWException if anything goes wrong while writing this attribute.
-     */
-    CloudEventAttributesWriter withAttribute(String name, String value) throws CloudEventRWException;
-
-    /**
-     * Set attribute with type {@link URI}.
-     *
-     * @param name  name of the attribute
-     * @param value value of the attribute
-     * @return self
-     * @throws CloudEventRWException if anything goes wrong while writing this attribute.
-     */
-    default CloudEventAttributesWriter withAttribute(String name, URI value) throws CloudEventRWException {
-        return withAttribute(name, value == null ? null : value.toString());
-    }
-
-    /**
-     * Set attribute with type {@link OffsetDateTime} attribute.
-     *
-     * @param name  name of the attribute
-     * @param value value of the attribute
-     * @return self
-     * @throws CloudEventRWException if anything goes wrong while writing this attribute.
-     */
-    default CloudEventAttributesWriter withAttribute(String name, OffsetDateTime value) throws CloudEventRWException {
-        return withAttribute(name, value == null ? null : Time.writeTime(name, value));
-    }
-
-}

api/src/main/java/io/cloudevents/rw/CloudEventContextReader.java

@@ -28,19 +28,11 @@ import javax.annotation.ParametersAreNonnullByDefault;
 public interface CloudEventContextReader {
 
     /**
-     * Visit self attributes using the provided writer
+     * Read the context attributes and extensions using the provided writer
      *
-     * @param writer Attributes writer
-     * @throws CloudEventRWException if something went wrong during the visit.
+     * @param writer context writer
+     * @throws CloudEventRWException if something went wrong during the read.
      */
-    void readAttributes(CloudEventAttributesWriter writer) throws CloudEventRWException;
-
-    /**
-     * Visit self extensions using the provided writer
-     *
-     * @param visitor Extensions writer
-     * @throws CloudEventRWException if something went wrong during the visit.
-     */
-    void readExtensions(CloudEventExtensionsWriter visitor) throws CloudEventRWException;
+    void readContext(CloudEventContextWriter writer) throws CloudEventRWException;
 
 }

api/src/main/java/io/cloudevents/rw/CloudEventContextWriter.java

@@ -0,0 +1,138 @@
+/*
+ * Copyright 2018-Present The CloudEvents Authors
+ * <p>
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * <p>
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * <p>
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package io.cloudevents.rw;
+
+import io.cloudevents.types.Time;
+
+import javax.annotation.ParametersAreNonnullByDefault;
+import java.net.URI;
+import java.time.OffsetDateTime;
+import java.util.Base64;
+
+/**
+ * Interface to write the context attributes/extensions from a {@link io.cloudevents.rw.CloudEventContextReader} to a new representation.
+ */
+@ParametersAreNonnullByDefault
+public interface CloudEventContextWriter {
+
+    /**
+     * Set attribute with type {@link String}.
+     * This setter should not be invoked for specversion, because the writer should
+     * already know the specversion or because it doesn't need it to correctly write the value.
+     *
+     * @param name  name of the attribute
+     * @param value value of the attribute
+     * @return self
+     * @throws CloudEventRWException    if anything goes wrong while writing this attribute.
+     * @throws IllegalArgumentException if you're trying to set the specversion attribute.
+     */
+    CloudEventContextWriter withContextAttribute(String name, String value) throws CloudEventRWException;
+
+    /**
+     * Set attribute with type {@link URI}.
+     * This setter should not be invoked for specversion, because the writer should
+     * already know the specversion or because it doesn't need it to correctly write the value.
+     *
+     * @param name  name of the attribute
+     * @param value value of the attribute
+     * @return self
+     * @throws CloudEventRWException if anything goes wrong while writing this attribute.
+     * @throws IllegalArgumentException if you're trying to set the specversion attribute.
+     */
+    default CloudEventContextWriter withContextAttribute(String name, URI value) throws CloudEventRWException {
+        return withContextAttribute(name, value.toString());
+    }
+
+    /**
+     * Set attribute with type {@link OffsetDateTime} attribute.
+     * This setter should not be invoked for specversion, because the writer should
+     * already know the specversion or because it doesn't need it to correctly write the value.
+     *
+     * @param name  name of the attribute
+     * @param value value of the attribute
+     * @return self
+     * @throws CloudEventRWException if anything goes wrong while writing this attribute.
+     * @throws IllegalArgumentException if you're trying to set the specversion attribute.
+     */
+    default CloudEventContextWriter withContextAttribute(String name, OffsetDateTime value) throws CloudEventRWException {
+        return withContextAttribute(name, Time.writeTime(name, value));
+    }
+
+    /**
+     * Set attribute with type {@link Number}.
+     * This setter should not be invoked for specversion, because the writer should
+     * already know the specversion or because it doesn't need it to correctly write the value.
+     *
+     * @param name  name of the attribute
+     * @param value value of the attribute
+     * @return self
+     * @throws CloudEventRWException if anything goes wrong while writing this extension.
+     * @throws IllegalArgumentException if you're trying to set the specversion attribute.
+     *
+     * @deprecated CloudEvent specification only permits {@link Integer} type as a
+     * numeric value.
+     */
+    default CloudEventContextWriter withContextAttribute(String name, Number value) throws CloudEventRWException {
+        return withContextAttribute(name, value.toString());
+    }
+
+    /**
+     * Set attribute with type {@link Integer}.
+     * This setter should not be invoked for specversion, because the writer should
+     * already know the specversion or because it doesn't need it to correctly write the value.
+     *
+     * @param name  name of the attribute
+     * @param value value of the attribute
+     * @return self
+     * @throws CloudEventRWException if anything goes wrong while writing this extension.
+     * @throws IllegalArgumentException if you're trying to set the specversion attribute.
+     */
+    default CloudEventContextWriter withContextAttribute(String name, Integer value) throws CloudEventRWException {
+        return withContextAttribute(name, value.toString());
+    }
+
+    /**
+     * Set attribute with type {@link Boolean} attribute.
+     * This setter should not be invoked for specversion, because the writer should
+     * already know the specversion or because it doesn't need it to correctly write the value.
+     *
+     * @param name  name of the attribute
+     * @param value value of the attribute
+     * @return self
+     * @throws CloudEventRWException if anything goes wrong while writing this extension.
+     * @throws IllegalArgumentException if you're trying to set the specversion attribute.
+     */
+    default CloudEventContextWriter withContextAttribute(String name, Boolean value) throws CloudEventRWException {
+        return withContextAttribute(name, value.toString());
+    }
+
+    /**
+     * Set attribute with a binary type.
+     * This setter should not be invoked for specversion, because the writer should
+     * already know the specversion or because it doesn't need it to correctly write the value.
+     *
+     * @param name  name of the attribute
+     * @param value value of the attribute
+     * @return self
+     * @throws CloudEventRWException if anything goes wrong while writing this extension.
+     * @throws IllegalArgumentException if you're trying to set the specversion attribute.
+     */
+    default CloudEventContextWriter withContextAttribute(String name, byte[] value) throws CloudEventRWException {
+        return withContextAttribute(name, Base64.getEncoder().encodeToString(value));
+    }
+}

api/src/main/java/io/cloudevents/rw/CloudEventDataMapper.java

@@ -23,6 +23,8 @@ import javax.annotation.ParametersAreNonnullByDefault;
 
 /**
  * Interface to convert a {@link CloudEventData} instance to another one.
+ *
+ * @param <R> the returned {@link CloudEventData} from this mapper.
  */
 @FunctionalInterface
 @ParametersAreNonnullByDefault
@@ -38,7 +40,7 @@ public interface CloudEventDataMapper<R extends CloudEventData> {
     R map(CloudEventData data) throws CloudEventRWException;
 
     /**
-     * No-op identity mapper which can be used as default when no mapper is provided.
+     * @return No-op identity mapper which can be used as default when no mapper is provided.
      */
     static CloudEventDataMapper<CloudEventData> identity() {
         return d -> d;

api/src/main/java/io/cloudevents/rw/CloudEventExtensionsWriter.java

@@ -1,61 +0,0 @@
-/*
- * Copyright 2018-Present The CloudEvents Authors
- * <p>
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- * <p>
- * http://www.apache.org/licenses/LICENSE-2.0
- * <p>
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- *
- */
-
-package io.cloudevents.rw;
-
-import java.net.URI;
-
-/**
- * Interface to write the extensions from a {@link io.cloudevents.rw.CloudEventReader} to a new representation.
- */
-public interface CloudEventExtensionsWriter {
-
-    /**
-     * Set an extension with type {@link String}.
-     *
-     * @param name  name of the extension
-     * @param value value of the extension
-     * @return self
-     * @throws CloudEventRWException if anything goes wrong while writing this extension.
-     */
-    CloudEventExtensionsWriter withExtension(String name, String value) throws CloudEventRWException;
-
-    /**
-     * Set attribute with type {@link URI}.
-     *
-     * @param name  name of the extension
-     * @param value value of the extension
-     * @return self
-     * @throws CloudEventRWException if anything goes wrong while writing this extension.
-     */
-    default CloudEventExtensionsWriter withExtension(String name, Number value) throws CloudEventRWException {
-        return withExtension(name, value == null ? null : value.toString());
-    }
-
-    /**
-     * Set attribute with type {@link Boolean} attribute.
-     *
-     * @param name  name of the extension
-     * @param value value of the extension
-     * @return self
-     * @throws CloudEventRWException if anything goes wrong while writing this extension.
-     */
-    default CloudEventExtensionsWriter withExtension(String name, Boolean value) throws CloudEventRWException {
-        return withExtension(name, value == null ? null : value.toString());
-    }
-
-}

api/src/main/java/io/cloudevents/rw/CloudEventRWException.java

@@ -17,6 +17,8 @@
 
 package io.cloudevents.rw;
 
+import io.cloudevents.lang.Nullable;
+
 /**
  * This class is the exception Protocol Binding and Event Format implementers can use to signal errors while serializing/deserializing CloudEvent.
  */
@@ -35,9 +37,9 @@ public class CloudEventRWException extends RuntimeException {
          */
         INVALID_ATTRIBUTE_NAME,
         /**
-         * The extension name is not valid,
-         * because it doesn't follow the <a href="https://github.com/cloudevents/spec/blob/v1.0/spec.md#attribute-naming-convention">naming convention</a>
-         * enforced by the CloudEvents spec.
+         * The extension name is not valid because it doesn't follow the naming convention enforced by the CloudEvents spec.
+         *
+         * @see <a href="https://github.com/cloudevents/spec/blob/v1.0/spec.md#attribute-naming-convention">naming convention</a>
          */
         INVALID_EXTENSION_NAME,
         /**
@@ -83,10 +85,17 @@ public class CloudEventRWException extends RuntimeException {
         this.kind = kind;
     }
 
+    /**
+     * @return the {@link CloudEventRWExceptionKind} associated to this exception instance.
+     */
     public CloudEventRWExceptionKind getKind() {
         return kind;
     }
 
+    /**
+     * @param specVersion the invalid input spec version
+     * @return a new {@link CloudEventRWException} instance
+     */
     public static CloudEventRWException newInvalidSpecVersion(String specVersion) {
         return new CloudEventRWException(
             CloudEventRWExceptionKind.INVALID_SPEC_VERSION,
@@ -94,6 +103,10 @@ public class CloudEventRWException extends RuntimeException {
         );
     }
 
+    /**
+     * @param attributeName the invalid attribute name
+     * @return a new {@link CloudEventRWException} instance
+     */
     public static CloudEventRWException newInvalidAttributeName(String attributeName) {
         return new CloudEventRWException(
             CloudEventRWExceptionKind.INVALID_ATTRIBUTE_NAME,
@@ -101,6 +114,10 @@ public class CloudEventRWException extends RuntimeException {
         );
     }
 
+    /**
+     * @param extensionName the invalid extension name
+     * @return a new {@link CloudEventRWException} instance
+     */
     public static CloudEventRWException newInvalidExtensionName(String extensionName) {
         return new CloudEventRWException(
             CloudEventRWExceptionKind.INVALID_EXTENSION_NAME,
@@ -108,6 +125,11 @@ public class CloudEventRWException extends RuntimeException {
         );
     }
 
+    /**
+     * @param attributeName the invalid attribute name
+     * @param clazz         the type of the attribute
+     * @return a new {@link CloudEventRWException} instance
+     */
     public static CloudEventRWException newInvalidAttributeType(String attributeName, Class<?> clazz) {
         return new CloudEventRWException(
             CloudEventRWExceptionKind.INVALID_ATTRIBUTE_TYPE,
@@ -115,7 +137,24 @@ public class CloudEventRWException extends RuntimeException {
         );
     }
 
-    public static CloudEventRWException newInvalidAttributeValue(String attributeName, Object value, Throwable cause) {
+    public static CloudEventRWException newInvalidAttributeType(String attributeName,Object value){
+        return new CloudEventRWException(
+            CloudEventRWExceptionKind.INVALID_ATTRIBUTE_TYPE,
+            "Invalid attribute/extension type for \""
+                + attributeName
+                + "\": Type" + value.getClass().getCanonicalName()
+                + ". Value: " + value
+
+        );
+    }
+
+    /**
+     * @param attributeName the invalid attribute name
+     * @param value         the value of the attribute
+     * @param cause         an optional cause identifying the eventual validation error
+     * @return a new {@link CloudEventRWException} instance
+     */
+    public static CloudEventRWException newInvalidAttributeValue(String attributeName, Object value, @Nullable Throwable cause) {
         return new CloudEventRWException(
             CloudEventRWExceptionKind.INVALID_ATTRIBUTE_VALUE,
             "Invalid attribute/extension value for \"" + attributeName + "\": " + value,
@@ -123,6 +162,11 @@ public class CloudEventRWException extends RuntimeException {
         );
     }
 
+    /**
+     * @param actual  the actual data type
+     * @param allowed the list of allowed data types
+     * @return a new {@link CloudEventRWException} instance
+     */
     public static CloudEventRWException newInvalidDataType(String actual, String... allowed) {
         String message;
         if (allowed.length == 0) {
@@ -136,6 +180,12 @@ public class CloudEventRWException extends RuntimeException {
         );
     }
 
+    /**
+     * @param cause the cause of the conversion failure
+     * @param from  the input data type
+     * @param to    the target data type
+     * @return a new {@link CloudEventRWException} instance
+     */
     public static CloudEventRWException newDataConversion(Throwable cause, String from, String to) {
         return new CloudEventRWException(
             CloudEventRWExceptionKind.DATA_CONVERSION,
@@ -144,6 +194,22 @@ public class CloudEventRWException extends RuntimeException {
         );
     }
 
+    /**
+     * @return a new {@link CloudEventRWException} instance.
+     */
+    public static CloudEventRWException newUnknownEncodingException() {
+        return new CloudEventRWException(
+            CloudEventRWExceptionKind.UNKNOWN_ENCODING,
+            "Could not parse. Unknown encoding. Invalid content type or spec version"
+        );
+    }
+
+    /**
+     * This wraps a {@link Throwable} in a new generic instance of this exception.
+     *
+     * @param cause the cause of the exception
+     * @return a new {@link CloudEventRWException} instance
+     */
     public static CloudEventRWException newOther(Throwable cause) {
         return new CloudEventRWException(
             CloudEventRWExceptionKind.OTHER,
@@ -151,10 +217,14 @@ public class CloudEventRWException extends RuntimeException {
         );
     }
 
-    public static CloudEventRWException newUnknownEncodingException() {
-        return new CloudEventRWException(
-            CloudEventRWExceptionKind.UNKNOWN_ENCODING,
-            "Could not parse. Unknown encoding. Invalid content type or spec version"
-        );
+    /**
+     *  An exception for use where none of the other variants are
+     *  appropriate.
+     *
+     * @param msg A description error message.
+     * @return a new {@link CloudEventRWException}
+     */
+    public static CloudEventRWException newOther(String msg){
+        return new CloudEventRWException(CloudEventRWExceptionKind.OTHER, msg);
     }
 }

api/src/main/java/io/cloudevents/rw/CloudEventReader.java

@@ -30,18 +30,29 @@ import javax.annotation.ParametersAreNonnullByDefault;
 public interface CloudEventReader {
 
     /**
-     * Visit self using the provided visitor factory
+     * Like {@link #read(CloudEventWriterFactory, CloudEventDataMapper)}, but with the identity {@link CloudEventDataMapper}.
      *
+     * @param <W> The type of the {@link CloudEventWriter} created by writerFactory
+     * @param <R> The return value of the {@link CloudEventWriter} created by writerFactory
      * @param writerFactory a factory that generates a visitor starting from the SpecVersion of the event
+     * @see #read(CloudEventWriterFactory, CloudEventDataMapper)
+     * @return the value returned by {@link CloudEventWriter#end()} or {@link CloudEventWriter#end(CloudEventData)}
      * @throws CloudEventRWException if something went wrong during the read.
      */
-    default <V extends CloudEventWriter<R>, R> R read(CloudEventWriterFactory<V, R> writerFactory) throws CloudEventRWException {
+    default <W extends CloudEventWriter<R>, R> R read(CloudEventWriterFactory<W, R> writerFactory) throws CloudEventRWException {
         return read(writerFactory, CloudEventDataMapper.identity());
     }
 
     /**
-     * Like {@link CloudEventReader#read(CloudEventWriterFactory)}, but providing a mapper for {@link io.cloudevents.CloudEventData} to be invoked when the data field is available.
+     * Read self using the provided writer factory.
+     *
+     * @param <W>           the {@link CloudEventWriter} type
+     * @param <R>           the return type of the {@link CloudEventWriter}
+     * @param writerFactory a factory that generates a visitor starting from the SpecVersion of the event
+     * @param mapper        the mapper to invoke when building the {@link CloudEventData}
+     * @return the value returned by {@link CloudEventWriter#end()} or {@link CloudEventWriter#end(CloudEventData)}
+     * @throws CloudEventRWException if something went wrong during the read.
      */
-    <V extends CloudEventWriter<R>, R> R read(CloudEventWriterFactory<V, R> writerFactory, CloudEventDataMapper<? extends CloudEventData> mapper) throws CloudEventRWException;
+    <W extends CloudEventWriter<R>, R> R read(CloudEventWriterFactory<W, R> writerFactory, CloudEventDataMapper<? extends CloudEventData> mapper) throws CloudEventRWException;
 
 }

api/src/main/java/io/cloudevents/rw/CloudEventWriter.java

@@ -25,18 +25,19 @@ import io.cloudevents.CloudEventData;
  *
  * @param <R> return value at the end of the write process
  */
-public interface CloudEventWriter<R> extends CloudEventAttributesWriter, CloudEventExtensionsWriter {
+public interface CloudEventWriter<R> extends CloudEventContextWriter {
 
     /**
-     * End the visit with a data field
+     * End the write with a data payload.
      *
+     * @param data the data to write
      * @return an eventual return value
      * @throws CloudEventRWException if the message writer cannot be ended.
      */
     R end(CloudEventData data) throws CloudEventRWException;
 
     /**
-     * End the visit
+     * End the write.
      *
      * @return an eventual return value
      * @throws CloudEventRWException if the message writer cannot be ended.

api/src/main/java/io/cloudevents/rw/CloudEventWriterFactory.java

@@ -19,8 +19,14 @@ package io.cloudevents.rw;
 
 import io.cloudevents.SpecVersion;
 
+/**
+ * This factory is used to enforce setting the {@link SpecVersion} as first step in the writing process.
+ *
+ * @param <W> The type of the {@link CloudEventWriter} created by this factory
+ * @param <R> The return value of the {@link CloudEventWriter} created by this factory
+ */
 @FunctionalInterface
-public interface CloudEventWriterFactory<V extends CloudEventWriter<R>, R> {
+public interface CloudEventWriterFactory<W extends CloudEventWriter<R>, R> {
 
     /**
      * Create a {@link CloudEventWriter} starting from the provided {@link SpecVersion}
@@ -29,5 +35,5 @@ public interface CloudEventWriterFactory<V extends CloudEventWriter<R>, R> {
      * @return the new writer
      * @throws CloudEventRWException if the spec version is invalid or the writer cannot be instantiated.
      */
-    V create(SpecVersion version) throws CloudEventRWException;
+    W create(SpecVersion version) throws CloudEventRWException;
 }

benchmarks/pom.xml

@@ -21,7 +21,7 @@
     <parent>
         <groupId>io.cloudevents</groupId>
         <artifactId>cloudevents-parent</artifactId>
-        <version>2.0.0-SNAPSHOT</version>
+        <version>4.1.0-SNAPSHOT</version>
     </parent>
 
     <artifactId>cloudevents-benchmarks</artifactId>
@@ -34,6 +34,7 @@
         <javac.target>1.8</javac.target>
         <!-- Name of the benchmark Uber-JAR to generate. -->
         <uberjar.name>benchmarks</uberjar.name>
+        <maven.javadoc.skip>true</maven.javadoc.skip>
     </properties>
 
     <dependencies>
@@ -58,6 +59,11 @@
             <artifactId>cloudevents-kafka</artifactId>
             <version>${project.version}</version>
         </dependency>
+        <dependency>
+            <groupId>io.cloudevents</groupId>
+            <artifactId>cloudevents-sql</artifactId>
+            <version>${project.version}</version>
+        </dependency>
 
         <dependency>
             <groupId>org.openjdk.jmh</groupId>
@@ -135,7 +141,7 @@
                 </plugin>
                 <plugin>
                     <artifactId>maven-install-plugin</artifactId>
-                    <version>2.5.1</version>
+                    <version>3.1.3</version>
                 </plugin>
                 <plugin>
                     <artifactId>maven-jar-plugin</artifactId>
@@ -155,7 +161,7 @@
                 </plugin>
                 <plugin>
                     <artifactId>maven-source-plugin</artifactId>
-                    <version>2.2.1</version>
+                    <version>3.3.0</version>
                 </plugin>
                 <plugin>
                     <artifactId>maven-surefire-plugin</artifactId>

benchmarks/src/main/java/io/cloudevents/bench/sql/CompileBenchmark.java

@@ -0,0 +1,35 @@
+package io.cloudevents.bench.sql;
+
+import io.cloudevents.sql.Parser;
+import org.openjdk.jmh.annotations.Benchmark;
+import org.openjdk.jmh.annotations.BenchmarkMode;
+import org.openjdk.jmh.annotations.Mode;
+import org.openjdk.jmh.infra.Blackhole;
+
+public class CompileBenchmark {
+
+    @Benchmark
+    @BenchmarkMode({Mode.Throughput, Mode.AverageTime})
+    public void testCompileSmallExpression(Blackhole bh) {
+        bh.consume(
+            Parser.parseDefault("(a + b + c) = 10 AND TRUE OR CONCAT('1', '2', id) = '123'")
+        );
+    }
+
+    @Benchmark
+    @BenchmarkMode({Mode.Throughput, Mode.AverageTime})
+    public void testCompileSmallTrueConstantExpression(Blackhole bh) {
+        bh.consume(
+            Parser.parseDefault("(1 + 2 + 3) = 10 AND TRUE OR CONCAT('1', '2', '3') = 123")
+        );
+    }
+
+    @Benchmark
+    @BenchmarkMode({Mode.Throughput, Mode.AverageTime})
+    public void testCompileSmallFalseConstantExpression(Blackhole bh) {
+        bh.consume(
+            Parser.parseDefault("(1 + 2 + 3) = 10 AND FALSE OR CONCAT('1', '2', '3') = 124")
+        );
+    }
+
+}

benchmarks/src/main/java/io/cloudevents/bench/sql/RunBenchmark.java

@@ -0,0 +1,92 @@
+package io.cloudevents.bench.sql;
+
+import io.cloudevents.CloudEvent;
+import io.cloudevents.core.builder.CloudEventBuilder;
+import io.cloudevents.sql.Expression;
+import io.cloudevents.sql.Parser;
+import org.openjdk.jmh.annotations.*;
+import org.openjdk.jmh.infra.Blackhole;
+
+import static io.cloudevents.core.test.Data.V1_WITH_JSON_DATA_WITH_EXT;
+
+public class RunBenchmark {
+
+    @State(Scope.Thread)
+    public static class TestCaseSmallExpression {
+        public CloudEvent event = CloudEventBuilder
+            .v1(V1_WITH_JSON_DATA_WITH_EXT)
+            .withExtension("a", "10")
+            .withExtension("b", 3)
+            .withExtension("c", "-3")
+            .build();
+        public Expression expression = Parser
+            .parseDefault("(a + b + c) = 10 AND TRUE OR CONCAT('1', '2', id) = '123'");
+    }
+
+    @State(Scope.Thread)
+    public static class TestCaseSmallTrueConstantExpression {
+        public CloudEvent event = CloudEventBuilder
+            .v1(V1_WITH_JSON_DATA_WITH_EXT)
+            .build();
+        public Expression expression = Parser
+            .parseDefault("(1 + 2 + 3) = 10 AND TRUE OR CONCAT('1', '2', '3') = 123");
+    }
+
+    @State(Scope.Thread)
+    public static class TestCaseSmallFalseConstantExpression {
+        public CloudEvent event = CloudEventBuilder
+            .v1(V1_WITH_JSON_DATA_WITH_EXT)
+            .build();
+        public Expression expression = Parser
+            .parseDefault("(1 + 2 + 3) = 10 AND FALSE OR CONCAT('1', '2', '3') = 124");
+    }
+
+    @Benchmark
+    @BenchmarkMode({Mode.Throughput, Mode.AverageTime})
+    public void testEvaluateSmallExpression(TestCaseSmallExpression testCase, Blackhole bh) {
+        bh.consume(
+            testCase.expression.evaluate(testCase.event)
+        );
+    }
+
+    @Benchmark
+    @BenchmarkMode({Mode.Throughput, Mode.AverageTime})
+    public void testTryEvaluateSmallExpression(TestCaseSmallExpression testCase, Blackhole bh) {
+        bh.consume(
+            testCase.expression.tryEvaluate(testCase.event)
+        );
+    }
+
+    @Benchmark
+    @BenchmarkMode({Mode.Throughput, Mode.AverageTime})
+    public void testEvaluateSmallTrueConstantExpression(TestCaseSmallTrueConstantExpression testCase, Blackhole bh) {
+        bh.consume(
+            testCase.expression.evaluate(testCase.event)
+        );
+    }
+
+    @Benchmark
+    @BenchmarkMode({Mode.Throughput, Mode.AverageTime})
+    public void testTryEvaluateSmallTrueConstantExpression(TestCaseSmallTrueConstantExpression testCase, Blackhole bh) {
+        bh.consume(
+            testCase.expression.tryEvaluate(testCase.event)
+        );
+    }
+
+    @Benchmark
+    @BenchmarkMode({Mode.Throughput, Mode.AverageTime})
+    public void testEvaluateSmallFalseConstantExpression(TestCaseSmallFalseConstantExpression testCase, Blackhole bh) {
+        bh.consume(
+            testCase.expression.evaluate(testCase.event)
+        );
+    }
+
+    @Benchmark
+    @BenchmarkMode({Mode.Throughput, Mode.AverageTime})
+    public void testTryEvaluateSmallFalseConstantExpression(TestCaseSmallFalseConstantExpression testCase, Blackhole bh) {
+        bh.consume(
+            testCase.expression.tryEvaluate(testCase.event)
+        );
+    }
+
+}

bom/pom.xml

@@ -0,0 +1,91 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+  ~ Copyright 2018-Present The CloudEvents Authors
+  ~ <p>
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~ <p>
+  ~ http://www.apache.org/licenses/LICENSE-2.0
+  ~ <p>
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  ~
+  -->
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <parent>
+        <groupId>io.cloudevents</groupId>
+        <artifactId>cloudevents-parent</artifactId>
+        <version>4.1.0-SNAPSHOT</version>
+    </parent>
+
+    <artifactId>cloudevents-bom</artifactId>
+    <name>CloudEvents - Bill of Materials</name>
+    <packaging>pom</packaging>
+
+    <dependencyManagement>
+        <dependencies>
+            <dependency>
+                <groupId>io.cloudevents</groupId>
+                <artifactId>cloudevents-api</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>io.cloudevents</groupId>
+                <artifactId>cloudevents-core</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>io.cloudevents</groupId>
+                <artifactId>cloudevents-json-jackson</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>io.cloudevents</groupId>
+                <artifactId>cloudevents-protobuf</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>io.cloudevents</groupId>
+                <artifactId>cloudevents-amqp-proton</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>io.cloudevents</groupId>
+                <artifactId>cloudevents-http-basic</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>io.cloudevents</groupId>
+                <artifactId>cloudevents-http-vertx</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>io.cloudevents</groupId>
+                <artifactId>cloudevents-http-restful-ws</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>io.cloudevents</groupId>
+                <artifactId>cloudevents-kafka</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>io.cloudevents</groupId>
+                <artifactId>cloudevents-spring</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>io.cloudevents</groupId>
+                <artifactId>cloudevents-sql</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+        </dependencies>
+    </dependencyManagement>
+</project>

core/README.md

@@ -1,67 +1,5 @@
 # CloudEvents Core
 
-[![Javadocs](http://www.javadoc.io/badge/io.cloudevents/cloudevents-core.svg?color=green)](http://www.javadoc.io/doc/io.cloudevents/cloudevents-core)
+Javadoc: [![Javadocs](http://www.javadoc.io/badge/io.cloudevents/cloudevents-core.svg?color=green)](http://www.javadoc.io/doc/io.cloudevents/cloudevents-core)
 
-The base classes, interfaces and low-level APIs to use CloudEvents.
-
-## How to Use
-
-For Maven based projects, use the following dependency:
-
-```xml
-<dependency>
-    <groupId>io.cloudevents</groupId>
-    <artifactId>cloudevents-api</artifactId>
-    <version>2.0.0.RC1</version>
-</dependency>
-```
-
-### Create an Event
-
-```java
-import io.cloudevents.CloudEvent;
-import io.cloudevents.core.builder.CloudEventBuilder;
-import java.net.URI;
-
-final CloudEvent event = CloudEventBuilder.v1()
-    .withId("000")
-    .withType("example.demo")
-    .withSource(URI.create("http://example.com"))
-    .withData("application/json", "{}".getBytes())
-    .build();
-```
-
-### Materialize an Extension
-
-CloudEvent extensions can be materialized in their respective POJOs:
-
-```java
-import io.cloudevents.core.extensions.DistributedTracingExtension;
-import io.cloudevents.core.extensions.ExtensionsParser;
-
-DistributedTracingExtension dte = ExtensionsParser.getInstance()
-    .parseExtension(DistributedTracingExtension.class, event);
-```
-
-### Using Event Formats
-
-The SDK implements [Event Formats](https://github.com/cloudevents/spec/blob/v1.0/spec.md#event-format) in submodules.
-To use them, you just need to add them as dependencies to your project and the SDK,
-through the `ServiceLoader` mechanism, will load them into the classpath.
-For example, to use the [JSON event format](https://github.com/cloudevents/spec/blob/v1.0/json-format.md) with Jackson,
-add `cloudevents-json-jackson` as a dependency and then:
-
-```java
-import io.cloudevents.core.format.EventFormatProvider;
-import io.cloudevents.jackson.JsonFormat;
-
-EventFormat format = EventFormatProvider
-  .getInstance()
-  .resolveFormat(JsonFormat.CONTENT_TYPE);
-
-// Serialize event
-byte[] serialized = format.serialize(event);
-
-// Deserialize event
-CloudEvent event = format.deserialize(bytes);
-```
+Documentation: https://cloudevents.github.io/sdk-java/core

core/pom.xml

@@ -22,7 +22,7 @@
     <parent>
         <groupId>io.cloudevents</groupId>
         <artifactId>cloudevents-parent</artifactId>
-        <version>2.0.0-SNAPSHOT</version>
+        <version>4.1.0-SNAPSHOT</version>
     </parent>
 
     <artifactId>cloudevents-core</artifactId>

core/src/main/java/io/cloudevents/core/CloudEventUtils.java

@@ -30,7 +30,7 @@ import io.cloudevents.rw.CloudEventRWException;
 import io.cloudevents.rw.CloudEventReader;
 
 /**
- * This class contains a set of utility methods to deal with conversions of io.cloudevents related interfaces
+ * This class contains a set of utility methods to deal with conversions of {@link io.cloudevents} related interfaces
  */
 public final class CloudEventUtils {
 
@@ -38,8 +38,7 @@ public final class CloudEventUtils {
 
     /**
      * Convert a {@link CloudEvent} to a {@link CloudEventReader}. This method provides a default implementation
-     * for CloudEvent that doesn't implement {@link CloudEventReader}
-     * for CloudEvent that doesn't implement CloudEventVisitable.
+     * for CloudEvent that doesn't implement {@link CloudEventReader}.
      * <p>
      * It's safe to use the returned {@link CloudEventReader} multiple times.
      *
@@ -94,6 +93,11 @@ public final class CloudEventUtils {
 
     /**
      * Get the data contained in {@code event} and map it using the provided mapper.
+     *
+     * @param event  the event eventually containing the data
+     * @param mapper the mapper to use to map the data
+     * @param <R>    the returned {@link CloudEventData} implementation from the provided mapper
+     * @return the data contained in {@code event} and mapped with {@code mapper}, if any, otherwise null
      */
     @Nullable
     public static <R extends CloudEventData> R mapData(CloudEvent event, CloudEventDataMapper<R> mapper) {

core/src/main/java/io/cloudevents/core/builder/CloudEventBuilder.java

@@ -17,18 +17,13 @@
 
 package io.cloudevents.core.builder;
 
-import java.net.URI;
-import java.time.OffsetDateTime;
+import io.cloudevents.*;
+import io.cloudevents.rw.CloudEventWriter;
 
 import javax.annotation.Nonnull;
 import javax.annotation.ParametersAreNullableByDefault;
-
-import io.cloudevents.CloudEvent;
-import io.cloudevents.CloudEventContext;
-import io.cloudevents.CloudEventData;
-import io.cloudevents.Extension;
-import io.cloudevents.SpecVersion;
-import io.cloudevents.rw.CloudEventWriter;
+import java.net.URI;
+import java.time.OffsetDateTime;
 
 /**
  * Builder interface to build a {@link CloudEvent}.
@@ -146,6 +141,28 @@ public interface CloudEventBuilder extends CloudEventWriter<CloudEvent> {
      */
     CloudEventBuilder withData(String dataContentType, URI dataSchema, CloudEventData data);
 
+    /**
+     * Remove the {@code datacontenttype}, {@code dataschema} and {@code data} from the event
+     *
+     * @return self
+     */
+    CloudEventBuilder withoutData();
+
+    /**
+     * Remove the {@code dataschema} from the event
+     *
+     * @return self
+     */
+    CloudEventBuilder withoutDataSchema();
+
+
+    /**
+     * Remove the {@code datacontenttype} from the event
+     *
+     * @return self
+     */
+    CloudEventBuilder withoutDataContentType();
+
     /**
      * Set an extension with provided key and string value
      *
@@ -153,7 +170,6 @@ public interface CloudEventBuilder extends CloudEventWriter<CloudEvent> {
      * @param value value of the extension attribute
      * @return self
      */
-    @Override
     CloudEventBuilder withExtension(@Nonnull String key, @Nonnull String value);
 
     /**
@@ -163,7 +179,6 @@ public interface CloudEventBuilder extends CloudEventWriter<CloudEvent> {
      * @param value value of the extension attribute
      * @return self
      */
-    @Override
     CloudEventBuilder withExtension(@Nonnull String key, @Nonnull Number value);
 
     /**
@@ -173,16 +188,42 @@ public interface CloudEventBuilder extends CloudEventWriter<CloudEvent> {
      * @param value value of the extension attribute
      * @return self
      */
-    @Override
     CloudEventBuilder withExtension(@Nonnull String key, @Nonnull Boolean value);
 
+    /**
+     * Set an extension with provided key and uri value
+     *
+     * @param key   key of the extension attribute
+     * @param value value of the extension attribute
+     * @return self
+     */
+    CloudEventBuilder withExtension(@Nonnull String key, @Nonnull URI value);
+
+    /**
+     * Set an extension with provided key and boolean value
+     *
+     * @param key   key of the extension attribute
+     * @param value value of the extension attribute
+     * @return self
+     */
+    CloudEventBuilder withExtension(@Nonnull String key, @Nonnull OffsetDateTime value);
+
+    /**
+     * Set an extension with provided key and binary value
+     *
+     * @param key   key of the extension attribute
+     * @param value value of the extension attribute
+     * @return self
+     */
+    CloudEventBuilder withExtension(@Nonnull String key, @Nonnull byte[] value);
+
     /**
      * Add to the builder all the extension key/values of the provided extension
      *
      * @param extension materialized extension to set in the builder
      * @return self
      */
-    CloudEventBuilder withExtension(@Nonnull Extension extension);
+    CloudEventBuilder withExtension(@Nonnull CloudEventExtension extension);
 
     /**
      * Remove from the the builder the provided extension key, if any
@@ -198,7 +239,7 @@ public interface CloudEventBuilder extends CloudEventWriter<CloudEvent> {
      * @param extension materialized extension to remove from the builder
      * @return self
      */
-    CloudEventBuilder withoutExtension(@Nonnull Extension extension);
+    CloudEventBuilder withoutExtension(@Nonnull CloudEventExtension extension);
 
     /**
      * Build the event
@@ -290,9 +331,9 @@ public interface CloudEventBuilder extends CloudEventWriter<CloudEvent> {
     static CloudEventBuilder fromContext(@Nonnull CloudEventContext context) {
         switch (context.getSpecVersion()) {
             case V1:
-            return new io.cloudevents.core.v1.CloudEventBuilder(context);
+                return new io.cloudevents.core.v1.CloudEventBuilder(context);
             case V03:
-            return new io.cloudevents.core.v03.CloudEventBuilder(context);
+                return new io.cloudevents.core.v03.CloudEventBuilder(context);
         }
         throw new IllegalStateException(
             "The provided spec version doesn't exist. Please make sure your io.cloudevents deps versions are aligned."

core/src/main/java/io/cloudevents/core/data/BytesCloudEventData.java

@@ -5,11 +5,15 @@ import io.cloudevents.CloudEventData;
 import java.util.Arrays;
 import java.util.Objects;
 
+/**
+ * An implementation of {@link CloudEventData} that wraps a byte array.
+ */
 public class BytesCloudEventData implements CloudEventData {
 
     private final byte[] value;
 
     /**
+     * @param value the bytes to wrap
      * @deprecated use {@link BytesCloudEventData#wrap(byte[])}
      */
     public BytesCloudEventData(byte[] value) {

core/src/main/java/io/cloudevents/core/data/PojoCloudEventData.java

@@ -5,6 +5,11 @@ import io.cloudevents.rw.CloudEventRWException;
 
 import java.util.Objects;
 
+/**
+ * An implementation of {@link CloudEventData} that wraps any POJO.
+ *
+ * @param <T> the type of the wrapped POJO.
+ */
 public class PojoCloudEventData<T> implements CloudEventData {
 
     /**
@@ -15,6 +20,11 @@ public class PojoCloudEventData<T> implements CloudEventData {
      */
     @FunctionalInterface
     public interface ToBytes<T> {
+        /**
+         * @param data the POJO to convert
+         * @return the serialized byte array.
+         * @throws Exception when something goes wrong during the conversion.
+         */
         byte[] convert(T data) throws Exception;
     }
 
@@ -36,6 +46,9 @@ public class PojoCloudEventData<T> implements CloudEventData {
         this.mapper = mapper;
     }
 
+    /**
+     * @return the wrapped POJO
+     */
     public T getValue() {
         return value;
     }
@@ -67,6 +80,11 @@ public class PojoCloudEventData<T> implements CloudEventData {
 
     /**
      * Wrap the provided data in a {@link PojoCloudEventData} serializable by the provided mapper.
+     *
+     * @param <T>    The type of {@code data}
+     * @param data   the POJO to wrap
+     * @param mapper converter from {@code data} to bytes, used to implement {@link #toBytes()}
+     * @return the new {@link PojoCloudEventData}
      */
     public static <T> PojoCloudEventData<T> wrap(T data, ToBytes<T> mapper) {
         return new PojoCloudEventData<>(data, mapper);

core/src/main/java/io/cloudevents/core/extensions/DatarefExtension.java

@@ -18,8 +18,9 @@
 package io.cloudevents.core.extensions;
 
 import io.cloudevents.CloudEventExtensions;
-import io.cloudevents.Extension;
+import io.cloudevents.CloudEventExtension;
 import io.cloudevents.core.extensions.impl.ExtensionUtils;
+
 import java.net.URI;
 import java.util.Collections;
 import java.util.HashSet;
@@ -27,19 +28,30 @@ import java.util.Set;
 
 /**
  * This extension supports the "Claim Check Pattern". It allows to specify a reference to a location where the event payload is stored.
+ *
  * @see <a href=https://github.com/cloudevents/spec/blob/v1.0/extensions/dataref.md>https://github.com/cloudevents/spec/blob/v1.0/extensions/dataref.md</a>
  */
-public final class DatarefExtension implements Extension {
+public final class DatarefExtension implements CloudEventExtension {
 
+    /**
+     * The key of the {@code dataref} extension
+     */
     public static final String DATAREF = "dataref";
+
     private static final Set<String> KEY_SET = Collections.unmodifiableSet(new HashSet<>(Collections.singletonList(DATAREF)));
 
     private URI dataref;
 
+    /**
+     * @return the {@code dataref} contained in this extension.
+     */
     public URI getDataref() {
         return dataref;
     }
 
+    /**
+     * @param dataref the uri to set as {@code dataref}.
+     */
     public void setDataref(URI dataref) {
         this.dataref = dataref;
     }
@@ -57,7 +69,7 @@ public final class DatarefExtension implements Extension {
         if (DATAREF.equals(key)) {
             return this.dataref.toString();
         }
-        throw ExtensionUtils.generateInvalidKeyException(this.getClass().getSimpleName(), key);
+        throw ExtensionUtils.generateInvalidKeyException(this.getClass(), key);
     }
 
     @Override

core/src/main/java/io/cloudevents/core/extensions/DistributedTracingExtension.java

@@ -18,40 +18,57 @@
 package io.cloudevents.core.extensions;
 
 import io.cloudevents.CloudEventExtensions;
-import io.cloudevents.Extension;
+import io.cloudevents.CloudEventExtension;
 import io.cloudevents.core.extensions.impl.ExtensionUtils;
 
-import java.util.Arrays;
-import java.util.Collections;
-import java.util.HashSet;
-import java.util.Set;
+import java.util.*;
 
 /**
  * This extension embeds context from Distributed Tracing so that distributed systems can include traces that span an event-driven system.
  *
- * @see <a href="https://github.com/cloudevents/spec/blob/master/extensions/distributed-tracing.md">https://github.com/cloudevents/spec/blob/master/extensions/distributed-tracing.md</a>
+ * @see <a href="https://github.com/cloudevents/spec/blob/main/extensions/distributed-tracing.md">https://github.com/cloudevents/spec/blob/main/extensions/distributed-tracing.md</a>
  */
-public final class DistributedTracingExtension implements Extension {
+public final class DistributedTracingExtension implements CloudEventExtension {
 
+    /**
+     * The key of the {@code traceparent} extension
+     */
     public static final String TRACEPARENT = "traceparent";
+
+    /**
+     * The key of the {@code tracestate} extension
+     */
     public static final String TRACESTATE = "tracestate";
+
     private static final Set<String> KEY_SET = Collections.unmodifiableSet(new HashSet<>(Arrays.asList(TRACEPARENT, TRACESTATE)));
 
     private String traceparent;
     private String tracestate;
 
+    /**
+     * @return the {@code traceparent} contained in this extension.
+     */
     public String getTraceparent() {
         return traceparent;
     }
 
+    /**
+     * @param traceparent the string to set as {@code traceparent}.
+     */
     public void setTraceparent(String traceparent) {
         this.traceparent = traceparent;
     }
 
+    /**
+     * @return the {@code tracestate} contained in this extension.
+     */
     public String getTracestate() {
         return tracestate;
     }
 
+    /**
+     * @param tracestate the string to set as {@code tracestate}.
+     */
     public void setTracestate(String tracestate) {
         this.tracestate = tracestate;
     }
@@ -76,7 +93,7 @@ public final class DistributedTracingExtension implements Extension {
             case TRACESTATE:
                 return this.tracestate;
         }
-        throw ExtensionUtils.generateInvalidKeyException(this.getClass().getSimpleName(), key);
+        throw ExtensionUtils.generateInvalidKeyException(this.getClass(), key);
     }
 
     @Override
@@ -93,35 +110,16 @@ public final class DistributedTracingExtension implements Extension {
     }
 
     @Override
-    public int hashCode() {
-        final int prime = 31;
-        int result = 1;
-        result = prime * result + ((traceparent == null) ? 0
-            : traceparent.hashCode());
-        result = prime * result + ((tracestate == null) ? 0
-            : tracestate.hashCode());
-        return result;
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        DistributedTracingExtension that = (DistributedTracingExtension) o;
+        return Objects.equals(getTraceparent(), that.getTraceparent()) &&
+            Objects.equals(getTracestate(), that.getTracestate());
     }
 
     @Override
-    public boolean equals(Object obj) {
-        if (this == obj)
-            return true;
-        if (obj == null)
-            return false;
-        if (getClass() != obj.getClass())
-            return false;
-        DistributedTracingExtension other = (DistributedTracingExtension) obj;
-        if (traceparent == null) {
-            if (other.traceparent != null)
-                return false;
-        } else if (!traceparent.equals(other.traceparent))
-            return false;
-        if (tracestate == null) {
-            if (other.tracestate != null)
-                return false;
-        } else if (!tracestate.equals(other.tracestate))
-            return false;
-        return true;
+    public int hashCode() {
+        return Objects.hash(getTraceparent(), getTracestate());
     }
 }

core/src/main/java/io/cloudevents/core/extensions/impl/ExtensionUtils.java

@@ -17,13 +17,23 @@
 
 package io.cloudevents.core.extensions.impl;
 
+import io.cloudevents.CloudEventExtension;
+
+/**
+ * Collection of utilities to deal with materialized extensions
+ */
 public final class ExtensionUtils {
 
     private ExtensionUtils() {
     }
 
-    public static IllegalArgumentException generateInvalidKeyException(String extensionName, String key) {
-        return new IllegalArgumentException(extensionName + " doesn't expect the attribute key \"" + key + "\"");
+    /**
+     * @param clazz the {@link CloudEventExtension} class
+     * @param key   the invalid key
+     * @return an {@link IllegalArgumentException} when trying to access a key of the extension not existing.
+     */
+    public static IllegalArgumentException generateInvalidKeyException(Class<? extends CloudEventExtension> clazz, String key) {
+        return new IllegalArgumentException(clazz.getName() + " doesn't expect the attribute key \"" + key + "\"");
     }
 
 }

core/src/main/java/io/cloudevents/core/format/ContentType.java

@@ -0,0 +1,72 @@
+/*
+ * Copyright 2018-Present The CloudEvents Authors
+ * <p>
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * <p>
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * <p>
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package io.cloudevents.core.format;
+
+import io.cloudevents.CloudEvent;
+import io.cloudevents.CloudEventData;
+import io.cloudevents.rw.CloudEventDataMapper;
+
+import javax.annotation.ParametersAreNonnullByDefault;
+import java.util.Collections;
+import java.util.Set;
+
+/**
+ * <p>A construct that aggregates a two-part identifier of file formats and format contents transmitted on the Internet.
+ *
+ * <p>The two parts of a {@code ContentType} are its <em>type</em> and a <em>subtype</em>; separated by a forward slash ({@code /}).
+ *
+ * <p>The constants enumerated by {@code ContentType} correspond <em>only</em> to the specialized formats supported by the Java™ SDK for CloudEvents.
+ *
+ * @see io.cloudevents.core.format.EventFormat
+ */
+@ParametersAreNonnullByDefault
+public enum ContentType {
+
+    /**
+     * Content type associated with the JSON event format
+     */
+    JSON("application/cloudevents+json"),
+    /**
+     * The content type for transports sending cloudevents in the protocol buffer format.
+     */
+    PROTO("application/cloudevents+protobuf"),
+    /**
+     * The content type for transports sending cloudevents in the compact Avro format.
+     */
+    AVRO_COMPACT("application/cloudevents+avrocompact"),
+    /**
+     * The content type for transports sending cloudevents in XML format.
+     */
+    XML("application/cloudevents+xml");
+
+    private String value;
+
+    private ContentType(String value) { this.value = value; }
+
+    /**
+     * Return a string consisting of the slash-delimited ({@code /}) two-part identifier for this {@code enum} constant.
+     */
+    public String value() { return value; }
+
+    /**
+     * Return a string consisting of the slash-delimited ({@code /}) two-part identifier for this {@code enum} constant.
+     */
+    @Override
+    public String toString() { return value(); }
+
+}

core/src/main/java/io/cloudevents/core/format/EventDeserializationException.java

@@ -21,7 +21,10 @@ package io.cloudevents.core.format;
  * Exception representing a deserialization error while using an {@link EventFormat}.
  */
 public class EventDeserializationException extends RuntimeException {
-    public EventDeserializationException(Throwable e) {
-        super(e);
+    /**
+     * @param cause the cause of the exception
+     */
+    public EventDeserializationException(Throwable cause) {
+        super(cause);
     }
 }

core/src/main/java/io/cloudevents/core/format/EventFormat.java

@@ -48,18 +48,21 @@ public interface EventFormat {
     byte[] serialize(CloudEvent event) throws EventSerializationException;
 
     /**
-     * Deserialize a byte array to a {@link CloudEvent}.
+     * Like {@link #deserialize(byte[], CloudEventDataMapper)}, but with the identity {@link CloudEventDataMapper}.
      *
-     * @param bytes the serialized event.
-     * @return the deserialized event.
-     * @throws EventDeserializationException if something goes wrong during deserialization.
+     * @see #deserialize(byte[], CloudEventDataMapper)
      */
     default CloudEvent deserialize(byte[] bytes) throws EventDeserializationException {
-        return this.deserialize(bytes, null);
+        return this.deserialize(bytes, CloudEventDataMapper.identity());
     }
 
     /**
-     * Like {@link EventFormat#deserialize(byte[])}, but allows a mapper that maps the parsed {@link io.cloudevents.CloudEventData} to another one.
+     * Deserialize a byte array to a {@link CloudEvent}.
+     *
+     * @param bytes  the serialized event.
+     * @param mapper the mapper to use to map the data.
+     * @return the deserialized event.
+     * @throws EventDeserializationException if something goes wrong during deserialization.
      */
     CloudEvent deserialize(byte[] bytes, CloudEventDataMapper<? extends CloudEventData> mapper) throws EventDeserializationException;
 

core/src/main/java/io/cloudevents/core/format/EventSerializationException.java

@@ -21,7 +21,10 @@ package io.cloudevents.core.format;
  * Exception representing a serialization error while using an {@link EventFormat}.
  */
 public class EventSerializationException extends RuntimeException {
-    public EventSerializationException(Throwable e) {
-        super(e);
+    /**
+     * @param cause the cause of the exception
+     */
+    public EventSerializationException(Throwable cause) {
+        super(cause);
     }
 }

core/src/main/java/io/cloudevents/core/impl/BaseCloudEvent.java

@@ -21,6 +21,8 @@ import io.cloudevents.CloudEvent;
 import io.cloudevents.CloudEventData;
 import io.cloudevents.rw.*;
 
+import java.net.URI;
+import java.time.OffsetDateTime;
 import java.util.HashMap;
 import java.util.Map;
 import java.util.Set;
@@ -52,26 +54,31 @@ public abstract class BaseCloudEvent implements CloudEvent, CloudEventReader, Cl
 
     @Override
     public <T extends CloudEventWriter<V>, V> V read(CloudEventWriterFactory<T, V> writerFactory, CloudEventDataMapper<? extends CloudEventData> mapper) throws CloudEventRWException, IllegalStateException {
-        CloudEventWriter<V> visitor = writerFactory.create(this.getSpecVersion());
-        this.readAttributes(visitor);
-        this.readExtensions(visitor);
+        CloudEventWriter<V> writer = writerFactory.create(this.getSpecVersion());
+        this.readContext(writer);
 
         if (this.data != null) {
-            return visitor.end(mapper.map(this.data));
+            return writer.end(mapper.map(this.data));
         }
 
-        return visitor.end();
+        return writer.end();
     }
 
-    public void readExtensions(CloudEventExtensionsWriter writer) throws CloudEventRWException {
+    protected void readExtensions(CloudEventContextWriter writer) throws CloudEventRWException {
         // TODO to be improved
         for (Map.Entry<String, Object> entry : this.extensions.entrySet()) {
             if (entry.getValue() instanceof String) {
-                writer.withExtension(entry.getKey(), (String) entry.getValue());
+                writer.withContextAttribute(entry.getKey(), (String) entry.getValue());
             } else if (entry.getValue() instanceof Number) {
-                writer.withExtension(entry.getKey(), (Number) entry.getValue());
+                writer.withContextAttribute(entry.getKey(), (Number) entry.getValue());
             } else if (entry.getValue() instanceof Boolean) {
-                writer.withExtension(entry.getKey(), (Boolean) entry.getValue());
+                writer.withContextAttribute(entry.getKey(), (Boolean) entry.getValue());
+            } else if (entry.getValue() instanceof URI) {
+                writer.withContextAttribute(entry.getKey(), (URI) entry.getValue());
+            } else if (entry.getValue() instanceof OffsetDateTime) {
+                writer.withContextAttribute(entry.getKey(), (OffsetDateTime) entry.getValue());
+            } else if (entry.getValue() instanceof byte[]) {
+                writer.withContextAttribute(entry.getKey(), (byte[]) entry.getValue());
             } else {
                 // This should never happen because we build that map only through our builders
                 throw new IllegalStateException("Illegal value inside extensions map: " + entry);

core/src/main/java/io/cloudevents/core/impl/BaseCloudEventBuilder.java

@@ -17,20 +17,21 @@
 
 package io.cloudevents.core.impl;
 
+import io.cloudevents.CloudEvent;
+import io.cloudevents.CloudEventContext;
+import io.cloudevents.CloudEventData;
+import io.cloudevents.CloudEventExtension;
+import io.cloudevents.core.builder.CloudEventBuilder;
+import io.cloudevents.core.data.BytesCloudEventData;
+import io.cloudevents.rw.CloudEventRWException;
+
+import javax.annotation.Nonnull;
 import java.net.URI;
 import java.time.OffsetDateTime;
 import java.util.HashMap;
 import java.util.Map;
 
-import javax.annotation.Nonnull;
-
-import io.cloudevents.CloudEvent;
-import io.cloudevents.CloudEventContext;
-import io.cloudevents.CloudEventData;
-import io.cloudevents.Extension;
-import io.cloudevents.core.builder.CloudEventBuilder;
-import io.cloudevents.core.data.BytesCloudEventData;
-import io.cloudevents.rw.CloudEventRWException;
+import static io.cloudevents.core.v03.CloudEventV03.SPECVERSION;
 
 public abstract class BaseCloudEventBuilder<SELF extends BaseCloudEventBuilder<SELF, T>, T extends CloudEvent> implements CloudEventBuilder {
 
@@ -97,6 +98,24 @@ public abstract class BaseCloudEventBuilder<SELF extends BaseCloudEventBuilder<S
         return this.self;
     }
 
+    @Override
+    public CloudEventBuilder withoutData() {
+        this.data = null;
+        return this.self;
+    }
+
+    @Override
+    public CloudEventBuilder withoutDataSchema() {
+        withDataSchema(null);
+        return this.self;
+    }
+
+    @Override
+    public CloudEventBuilder withoutDataContentType() {
+        withDataContentType(null);
+        return this.self;
+    }
+
     public SELF withExtension(@Nonnull String key, @Nonnull String value) {
         if (!isValidExtensionName(key)) {
             throw CloudEventRWException.newInvalidExtensionName(key);
@@ -105,6 +124,9 @@ public abstract class BaseCloudEventBuilder<SELF extends BaseCloudEventBuilder<S
         return self;
     }
 
+    // @TODO - I think this method should be removed/deprecated
+    // **Number** Is NOT a valid CE Context atrribute type.
+
     public SELF withExtension(@Nonnull String key, @Nonnull Number value) {
         if (!isValidExtensionName(key)) {
             throw CloudEventRWException.newInvalidExtensionName(key);
@@ -113,6 +135,14 @@ public abstract class BaseCloudEventBuilder<SELF extends BaseCloudEventBuilder<S
         return self;
     }
 
+    public SELF withExtension(@Nonnull String key, @Nonnull Integer value) {
+        if (!isValidExtensionName(key)) {
+            throw CloudEventRWException.newInvalidExtensionName(key);
+        }
+        this.extensions.put(key, value);
+        return self;
+    }
+
     public SELF withExtension(@Nonnull String key, @Nonnull Boolean value) {
         if (!isValidExtensionName(key)) {
             throw CloudEventRWException.newInvalidExtensionName(key);
@@ -121,6 +151,33 @@ public abstract class BaseCloudEventBuilder<SELF extends BaseCloudEventBuilder<S
         return self;
     }
 
+    @Override
+    public SELF withExtension(@Nonnull String key, @Nonnull URI value) {
+        if (!isValidExtensionName(key)) {
+            throw CloudEventRWException.newInvalidExtensionName(key);
+        }
+        this.extensions.put(key, value);
+        return self;
+    }
+
+    @Override
+    public SELF withExtension(@Nonnull String key, @Nonnull OffsetDateTime value) {
+        if (!isValidExtensionName(key)) {
+            throw CloudEventRWException.newInvalidExtensionName(key);
+        }
+        this.extensions.put(key, value);
+        return self;
+    }
+
+    @Override
+    public CloudEventBuilder withExtension(@Nonnull String key, @Nonnull byte[] value) {
+        if (!isValidExtensionName(key)) {
+            throw CloudEventRWException.newInvalidExtensionName(key);
+        }
+        this.extensions.put(key, value);
+        return self;
+    }
+
     @Override
     public SELF withoutExtension(@Nonnull String key) {
         this.extensions.remove(key);
@@ -128,12 +185,12 @@ public abstract class BaseCloudEventBuilder<SELF extends BaseCloudEventBuilder<S
     }
 
     @Override
-    public SELF withoutExtension(@Nonnull Extension extension) {
+    public SELF withoutExtension(@Nonnull CloudEventExtension extension) {
         extension.getKeys().forEach(this::withoutExtension);
         return self;
     }
 
-    public SELF withExtension(@Nonnull Extension extension) {
+    public SELF withExtension(@Nonnull CloudEventExtension extension) {
         for (String key : extension.getKeys()) {
             Object value = extension.getValue(key);
             if (value != null) {
@@ -161,20 +218,23 @@ public abstract class BaseCloudEventBuilder<SELF extends BaseCloudEventBuilder<S
     protected static IllegalStateException createMissingAttributeException(String attributeName) {
         return new IllegalStateException("Attribute '" + attributeName + "' cannot be null");
     }
+
+    protected static IllegalStateException createEmptyAttributeException(String attributeName) {
+        return new IllegalStateException("Attribute '" + attributeName + "' cannot be empty");
+    }
+
     /**
-     * Validates the extension name as defined in  CloudEvents spec
-     * See <a href="https://github.com/cloudevents/spec/blob/master/spec.md#attribute-naming-convention">attribute-naming-convention</a>
+     * Validates the extension name as defined in  CloudEvents spec.
+     *
      * @param name the extension name
      * @return true if extension name is valid, false otherwise
+     * @see <a href="https://github.com/cloudevents/spec/blob/main/cloudevents/spec.md#naming-conventions">attribute-naming-conventions</a>
      */
     private static boolean isValidExtensionName(String name) {
-        if(name.length() > 20){
-            return false;
-        }
-        char[] chars = name.toCharArray();
-        for (char c: chars)
-        if (!isValidChar(c)) {
-            return false;
+        for (int i = 0; i < name.length(); i++) {
+            if (!isValidChar(name.charAt(i))) {
+                return false;
+            }
         }
         return true;
     }
@@ -182,4 +242,10 @@ public abstract class BaseCloudEventBuilder<SELF extends BaseCloudEventBuilder<S
     private static boolean isValidChar(char c) {
         return (c >= 'a' && c <= 'z') || (c >= '0' && c <= '9');
     }
+
+    protected void requireValidAttributeWrite(String name) {
+        if (name.equals(SPECVERSION)) {
+            throw new IllegalArgumentException("You should not set the specversion attribute through withContextAttribute methods");
+        }
+    }
 }

core/src/main/java/io/cloudevents/core/impl/CloudEventContextReaderAdapter.java

@@ -18,9 +18,12 @@
 package io.cloudevents.core.impl;
 
 import io.cloudevents.CloudEventContext;
-import io.cloudevents.rw.CloudEventAttributesWriter;
 import io.cloudevents.rw.CloudEventContextReader;
-import io.cloudevents.rw.CloudEventExtensionsWriter;
+import io.cloudevents.rw.CloudEventContextWriter;
+import io.cloudevents.rw.CloudEventRWException;
+
+import java.net.URI;
+import java.time.OffsetDateTime;
 
 public class CloudEventContextReaderAdapter implements CloudEventContextReader {
 
@@ -30,41 +33,47 @@ public class CloudEventContextReaderAdapter implements CloudEventContextReader {
         this.event = event;
     }
 
-    @Override
-    public void readAttributes(CloudEventAttributesWriter writer) throws RuntimeException {
-        writer.withAttribute("id", event.getId());
-        writer.withAttribute("source", event.getSource());
-        writer.withAttribute("type", event.getType());
+    public void readAttributes(CloudEventContextWriter writer) throws RuntimeException {
+        writer.withContextAttribute("id", event.getId());
+        writer.withContextAttribute("source", event.getSource());
+        writer.withContextAttribute("type", event.getType());
         if (event.getDataContentType() != null) {
-            writer.withAttribute("datacontenttype", event.getDataContentType());
+            writer.withContextAttribute("datacontenttype", event.getDataContentType());
         }
         if (event.getDataSchema() != null) {
-            writer.withAttribute("dataschema", event.getDataSchema());
+            writer.withContextAttribute("dataschema", event.getDataSchema());
         }
         if (event.getSubject() != null) {
-            writer.withAttribute("subject", event.getSubject());
+            writer.withContextAttribute("subject", event.getSubject());
         }
         if (event.getTime() != null) {
-            writer.withAttribute("time", event.getTime());
+            writer.withContextAttribute("time", event.getTime());
         }
     }
 
-    @Override
-    public void readExtensions(CloudEventExtensionsWriter writer) throws RuntimeException {
+    public void readExtensions(CloudEventContextWriter writer) throws RuntimeException {
         for (String key : event.getExtensionNames()) {
             Object value = event.getExtension(key);
             if (value instanceof String) {
-                writer.withExtension(key, (String) value);
+                writer.withContextAttribute(key, (String) value);
             } else if (value instanceof Number) {
-                writer.withExtension(key, (Number) value);
+                writer.withContextAttribute(key, (Number) value);
             } else if (value instanceof Boolean) {
-                writer.withExtension(key, (Boolean) value);
+                writer.withContextAttribute(key, (Boolean) value);
+            } else if (value instanceof URI) {
+                writer.withContextAttribute(key, (URI) value);
+            } else if (value instanceof OffsetDateTime) {
+                writer.withContextAttribute(key, (OffsetDateTime) value);
             } else {
                 // This should never happen because we build that map only through our builders
                 throw new IllegalStateException("Illegal value inside extensions map: " + key + " " + value);
             }
         }
-        ;
     }
 
+    @Override
+    public void readContext(CloudEventContextWriter writer) throws CloudEventRWException {
+        this.readAttributes(writer);
+        this.readExtensions(writer);
+    }
 }

core/src/main/java/io/cloudevents/core/impl/StringUtils.java

@@ -0,0 +1,31 @@
+/*
+ * Copyright 2018-Present The CloudEvents Authors
+ * <p>
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * <p>
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * <p>
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package io.cloudevents.core.impl;
+
+import javax.annotation.Nonnull;
+
+final public class StringUtils {
+
+    private StringUtils() {
+        // Prevent construction.
+    }
+
+    public static boolean startsWithIgnoreCase(@Nonnull final String s, @Nonnull final String prefix) {
+        return s.regionMatches(true /* ignoreCase */, 0, prefix, 0, prefix.length());
+    }
+}

core/src/main/java/io/cloudevents/core/message/Encoding.java

@@ -21,6 +21,12 @@ package io.cloudevents.core.message;
  * One of the possible encodings of a <a href="https://github.com/cloudevents/spec/blob/v1.0/spec.md#message">CloudEvent message</a>
  */
 public enum Encoding {
+    /**
+     * Structured mode
+     */
     STRUCTURED,
+    /**
+     * Binary mode
+     */
     BINARY
 }

core/src/main/java/io/cloudevents/core/message/MessageReader.java

@@ -19,41 +19,50 @@ package io.cloudevents.core.message;
 
 import io.cloudevents.CloudEvent;
 import io.cloudevents.CloudEventData;
+import io.cloudevents.SpecVersion;
 import io.cloudevents.core.CloudEventUtils;
 import io.cloudevents.rw.*;
 
 import javax.annotation.ParametersAreNonnullByDefault;
 
 /**
- * Represents a <a href="https://github.com/cloudevents/spec/blob/v1.0/spec.md#message">CloudEvent message</a>.
+ * Represents a <a href="https://github.com/cloudevents/spec/blob/v1.0/spec.md#message">CloudEvent message</a> reader.
+ * <p>
+ * This class expands the {@link CloudEventReader} to define reading both binary and structured messages.
  */
 @ParametersAreNonnullByDefault
 public interface MessageReader extends StructuredMessageReader, CloudEventReader {
 
     /**
-     * Visit the message as binary encoded event using the provided visitor factory.
+     * Like {@link #read(CloudEventWriterFactory, CloudEventDataMapper)}, but with the identity {@link CloudEventDataMapper}.
      *
-     * @param writerFactory a factory that generates a visitor starting from the SpecVersion of the event
-     * @throws CloudEventRWException if something went wrong during the visit.
-     * @throws IllegalStateException if the message is not in binary encoding.
+     * @see #read(CloudEventWriterFactory, CloudEventDataMapper)
      */
-    default <V extends CloudEventWriter<R>, R> R read(CloudEventWriterFactory<V, R> writerFactory) throws CloudEventRWException, IllegalStateException {
+    default <W extends CloudEventWriter<R>, R> R read(CloudEventWriterFactory<W, R> writerFactory) throws CloudEventRWException, IllegalStateException {
         return read(writerFactory, CloudEventDataMapper.identity());
     }
 
     /**
-     * Like {@link MessageReader#read(CloudEventWriterFactory)}, but providing a mapper for {@link io.cloudevents.CloudEventData} to be invoked when the data field is available.
+     * Read the message as binary encoded message using the provided writer factory.
+     *
+     * @param <W>           the {@link CloudEventWriter} type
+     * @param <R>           the return type of the {@link CloudEventWriter}
+     * @param writerFactory a factory that generates a reader starting from the {@link SpecVersion} of the event
+     * @param mapper        the mapper to use to map the data, if any.
+     * @throws CloudEventRWException if something went wrong during the visit.
+     * @throws IllegalStateException if the message is not in binary encoding.
      */
-    <V extends CloudEventWriter<R>, R> R read(CloudEventWriterFactory<V, R> writerFactory, CloudEventDataMapper<? extends CloudEventData> mapper) throws CloudEventRWException, IllegalStateException;
+    <W extends CloudEventWriter<R>, R> R read(CloudEventWriterFactory<W, R> writerFactory, CloudEventDataMapper<? extends CloudEventData> mapper) throws CloudEventRWException, IllegalStateException;
 
     /**
-     * Visit the message as structured encoded event using the provided visitor
+     * Read the message as structured encoded message using the provided writer
      *
-     * @param visitor Structured Message visitor
+     * @param <R>    the return type of the {@link StructuredMessageWriter}
+     * @param writer Structured Message writer
      * @throws CloudEventRWException if something went wrong during the visit.
-     * @throws IllegalStateException    if the message is not in structured encoding.
+     * @throws IllegalStateException if the message is not in structured encoding.
      */
-    <T> T read(StructuredMessageWriter<T> visitor) throws CloudEventRWException, IllegalStateException;
+    <R> R read(StructuredMessageWriter<R> writer) throws CloudEventRWException, IllegalStateException;
 
     /**
      * @return The message encoding
@@ -64,38 +73,41 @@ public interface MessageReader extends StructuredMessageReader, CloudEventReader
      * Read the content of this object using a {@link MessageWriter}. This method allows to transcode an event from one transport to another without
      * converting it to {@link CloudEvent}. The resulting encoding will be the same as the original encoding.
      *
-     * @param visitor the MessageVisitor accepting this Message
-     * @return The return value of the MessageVisitor
+     * @param <BW>   the {@link CloudEventWriter} type
+     * @param <R>    the return type of both {@link CloudEventWriter} and {@link StructuredMessageWriter}
+     * @param writer the {@link MessageWriter} accepting this Message
+     * @return The return value of the {@link MessageWriter}
      * @throws CloudEventRWException if something went wrong during the visit.
      * @throws IllegalStateException if the message has an unknown encoding.
      */
-    default <BV extends CloudEventWriter<R>, R> R read(MessageWriter<BV, R> visitor) throws CloudEventRWException, IllegalStateException {
+    default <BW extends CloudEventWriter<R>, R> R read(MessageWriter<BW, R> writer) throws CloudEventRWException, IllegalStateException {
         switch (getEncoding()) {
             case BINARY:
-                return this.read((CloudEventWriterFactory<BV, R>) visitor);
+                return this.read((CloudEventWriterFactory<BW, R>) writer);
             case STRUCTURED:
-                return this.read((StructuredMessageWriter<R>) visitor);
+                return this.read((StructuredMessageWriter<R>) writer);
             default:
-                throw new IllegalStateException("Unknown encoding");
+                throw new IllegalStateException(
+                    "The provided Encoding doesn't exist. Please make sure your io.cloudevents deps versions are aligned."
+                );
         }
     }
 
     /**
-     * Translate this message into a {@link CloudEvent} representation.
+     * Like {@link #toEvent(CloudEventDataMapper)}, but with the identity {@link CloudEventDataMapper}.
      *
-     * @return A {@link CloudEvent} with the contents of this message.
-     * @throws CloudEventRWException if something went wrong during the visit.
-     * @throws IllegalStateException    if the message has an unknown encoding.
+     * @see #toEvent(CloudEventDataMapper)
      */
     default CloudEvent toEvent() throws CloudEventRWException, IllegalStateException {
         return toEvent(CloudEventDataMapper.identity());
     }
 
     /**
-     * Translate this message into a {@link CloudEvent} representation.
+     * Translate this message into a {@link CloudEvent} representation, mapping the data with the provided {@code mapper}.
      *
+     * @param mapper the mapper to use to map the data, if any.
      * @return A {@link CloudEvent} with the contents of this message.
-     * @throws CloudEventRWException if something went wrong during the visit.
+     * @throws CloudEventRWException if something went wrong during the read.
      * @throws IllegalStateException if the message has an unknown encoding.
      */
     default CloudEvent toEvent(CloudEventDataMapper<? extends CloudEventData> mapper) throws CloudEventRWException, IllegalStateException {
@@ -105,7 +117,9 @@ public interface MessageReader extends StructuredMessageReader, CloudEventReader
             case STRUCTURED:
                 return this.read((format, value) -> format.deserialize(value, mapper));
             default:
-                throw new IllegalStateException("Unknown encoding");
+                throw new IllegalStateException(
+                    "The provided Encoding doesn't exist. Please make sure your io.cloudevents deps versions are aligned."
+                );
         }
     }
 

core/src/main/java/io/cloudevents/core/message/StructuredMessageReader.java

@@ -34,11 +34,15 @@ import javax.annotation.ParametersAreNonnullByDefault;
 public interface StructuredMessageReader {
 
     /**
-     * @param visitor
+     * Read self using the provided writer.
+     *
+     * @param <R>    the return type of the {@link StructuredMessageWriter}
+     * @param writer the writer to use to write out the message
+     * @return the return value returned by {@link StructuredMessageWriter#setEvent(EventFormat, byte[])}
      * @throws CloudEventRWException If something went wrong when
      * @throws IllegalStateException If the message is not a valid structured message
      */
-    <T> T read(StructuredMessageWriter<T> visitor) throws CloudEventRWException, IllegalStateException;
+    <R> R read(StructuredMessageWriter<R> writer) throws CloudEventRWException, IllegalStateException;
 
     default CloudEvent toEvent() throws CloudEventRWException, IllegalStateException {
         return this.read(EventFormat::deserialize);
@@ -49,9 +53,9 @@ public interface StructuredMessageReader {
     }
 
     /**
-     * Create a generic structured message from a {@link CloudEvent}
+     * Create a generic structured message from a {@link CloudEvent}.
      *
-     * @param event
+     * @param event the event to convert to {@link StructuredMessageReader}
      * @param contentType content type to use to resolve the {@link EventFormat}
      * @return null if format was not found, otherwise returns the built message
      */
@@ -60,10 +64,10 @@ public interface StructuredMessageReader {
     }
 
     /**
-     * Create a generic structured message from a {@link CloudEvent}
+     * Create a generic structured message from a {@link CloudEvent}.
      *
-     * @param event
-     * @param format
+     * @param event the event to convert to {@link StructuredMessageReader}
+     * @param format the format to use to perform the conversion
      * @return null if format was not found, otherwise returns the built message
      */
     static StructuredMessageReader from(CloudEvent event, EventFormat format) {

core/src/main/java/io/cloudevents/core/message/StructuredMessageWriter.java

@@ -25,15 +25,15 @@ import javax.annotation.ParametersAreNonnullByDefault;
 /**
  * Interface to write the {@link MessageReader} content (CloudEvents attributes, extensions and payload) to a new representation structured representation.
  *
- * @param <T> return value at the end of the write process.
+ * @param <R> return value at the end of the write process.
  */
 @ParametersAreNonnullByDefault
 @FunctionalInterface
-public interface StructuredMessageWriter<T> {
+public interface StructuredMessageWriter<R> {
 
     /**
      * Write an event using the provided {@link EventFormat}.
      */
-    T setEvent(EventFormat format, byte[] value) throws CloudEventRWException;
+    R setEvent(EventFormat format, byte[] value) throws CloudEventRWException;
 
 }

core/src/main/java/io/cloudevents/core/message/impl/BaseBinaryMessageReader.java

@@ -22,6 +22,9 @@ import io.cloudevents.core.message.MessageReader;
 import io.cloudevents.core.message.StructuredMessageWriter;
 import io.cloudevents.rw.CloudEventRWException;
 
+/**
+ * Base {@link MessageReader} implementation for a binary message
+ */
 public abstract class BaseBinaryMessageReader implements MessageReader {
 
     @Override
@@ -30,7 +33,7 @@ public abstract class BaseBinaryMessageReader implements MessageReader {
     }
 
     @Override
-    public <T> T read(StructuredMessageWriter<T> visitor) throws CloudEventRWException, IllegalStateException {
+    public <T> T read(StructuredMessageWriter<T> writer) throws CloudEventRWException, IllegalStateException {
         throw MessageUtils.generateWrongEncoding(Encoding.STRUCTURED, Encoding.BINARY);
     }
 }

core/src/main/java/io/cloudevents/core/message/impl/BaseGenericBinaryMessageReaderImpl.java

@@ -56,18 +56,17 @@ public abstract class BaseGenericBinaryMessageReaderImpl<HK, HV> extends BaseBin
         // This implementation avoids to use visitAttributes and visitExtensions
         // in order to complete the visit in one loop
         this.forEachHeader((key, value) -> {
+            if (value == null) {
+                return;
+            }
             if (isContentTypeHeader(key)) {
-                visitor.withAttribute(CloudEventV1.DATACONTENTTYPE, toCloudEventsValue(value));
+                visitor.withContextAttribute(CloudEventV1.DATACONTENTTYPE, toCloudEventsValue(value));
             } else if (isCloudEventsHeader(key)) {
                 String name = toCloudEventsKey(key);
                 if (name.equals(CloudEventV1.SPECVERSION)) {
                     return;
                 }
-                if (this.version.getAllAttributes().contains(name)) {
-                    visitor.withAttribute(name, toCloudEventsValue(value));
-                } else {
-                    visitor.withExtension(name, toCloudEventsValue(value));
-                }
+                visitor.withContextAttribute(name, toCloudEventsValue(value));
             }
         });
 
@@ -79,14 +78,35 @@ public abstract class BaseGenericBinaryMessageReaderImpl<HK, HV> extends BaseBin
         return visitor.end();
     }
 
+    /**
+     * @param key header key
+     * @return true if this header is the content type header, false otherwise
+     */
     protected abstract boolean isContentTypeHeader(HK key);
 
+    /**
+     * @param key header key
+     * @return true if this header is a CloudEvents header, false otherwise
+     */
     protected abstract boolean isCloudEventsHeader(HK key);
 
+    /**
+     * @param key header key
+     * @return the key converted to a CloudEvents context attribute/extension name
+     */
     protected abstract String toCloudEventsKey(HK key);
 
+    /**
+     * Iterate over all the headers in the headers map.
+     *
+     * @param fn header consumer
+     */
     protected abstract void forEachHeader(BiConsumer<HK, HV> fn);
 
+    /**
+     * @param value header key
+     * @return the value converted to a valid CloudEvents attribute value as {@link String}.
+     */
     protected abstract String toCloudEventsValue(HV value);
 
 }

core/src/main/java/io/cloudevents/core/message/impl/BaseStructuredMessageReader.java

@@ -24,6 +24,9 @@ import io.cloudevents.rw.CloudEventDataMapper;
 import io.cloudevents.rw.CloudEventWriter;
 import io.cloudevents.rw.CloudEventWriterFactory;
 
+/**
+ * Base {@link MessageReader} implementation for a structured message
+ */
 public abstract class BaseStructuredMessageReader implements MessageReader {
 
     @Override

core/src/main/java/io/cloudevents/core/message/impl/GenericStructuredMessageReader.java

@@ -24,6 +24,9 @@ import io.cloudevents.core.provider.EventFormatProvider;
 import io.cloudevents.lang.Nullable;
 import io.cloudevents.rw.CloudEventRWException;
 
+/**
+ * Generic implementation of a structured message.
+ */
 public class GenericStructuredMessageReader extends BaseStructuredMessageReader {
 
     private final EventFormat format;
@@ -35,8 +38,8 @@ public class GenericStructuredMessageReader extends BaseStructuredMessageReader
     }
 
     @Override
-    public <T> T read(StructuredMessageWriter<T> visitor) throws CloudEventRWException, IllegalStateException {
-        return visitor.setEvent(format, payload);
+    public <T> T read(StructuredMessageWriter<T> writer) throws CloudEventRWException, IllegalStateException {
+        return writer.setEvent(format, payload);
     }
 
     /**

core/src/main/java/io/cloudevents/core/message/impl/MessageUtils.java

@@ -22,6 +22,7 @@ import io.cloudevents.core.format.EventFormat;
 import io.cloudevents.core.message.Encoding;
 import io.cloudevents.core.message.MessageReader;
 import io.cloudevents.core.provider.EventFormatProvider;
+import io.cloudevents.rw.CloudEventRWException;
 
 import java.util.Map;
 import java.util.function.Function;
@@ -31,25 +32,43 @@ import java.util.stream.Stream;
 
 import static io.cloudevents.rw.CloudEventRWException.newUnknownEncodingException;
 
+/**
+ * Collection of utilities useful to implement {@link MessageReader} and {@link io.cloudevents.core.message.MessageWriter} related code.
+ */
 public class MessageUtils {
 
     /**
      * Common flow to parse an incoming message that could be structured or binary.
+     *
+     * @param contentTypeHeaderReader  supplier that returns the content type header, if any
+     * @param structuredMessageFactory factory to create the structured {@link MessageReader} from the provided {@link EventFormat}
+     * @param specVersionHeaderReader  supplier that returns the spec version header, if any
+     * @param binaryMessageFactory     factory to create the binary {@link MessageReader} from the provided {@link SpecVersion}
+     * @return the instantiated {@link MessageReader}
+     * @throws CloudEventRWException if something goes wrong while resolving the {@link SpecVersion} or if the message has unknown encoding
      */
     public static MessageReader parseStructuredOrBinaryMessage(
         Supplier<String> contentTypeHeaderReader,
         Function<EventFormat, MessageReader> structuredMessageFactory,
         Supplier<String> specVersionHeaderReader,
         Function<SpecVersion, MessageReader> binaryMessageFactory
-    ) {
+    ) throws CloudEventRWException {
         // Let's try structured mode
         String ct = contentTypeHeaderReader.get();
         if (ct != null) {
             EventFormat format = EventFormatProvider.getInstance().resolveFormat(ct);
             if (format != null) {
                 return structuredMessageFactory.apply(format);
+            } else {
+                /**
+                 * The format wasn't one we support, but if it's part of the
+                 * CloudEvent family it indicates it's a structured
+                 * representation that we can't interpret.
+                 */
+                if (ct.startsWith("application/cloudevents")) {
+                    throw newUnknownEncodingException();
+                }
             }
-
         }
 
         // Let's try binary mode
@@ -77,6 +96,11 @@ public class MessageUtils {
             .collect(Collectors.toMap(Function.identity(), headerNameMapping));
     }
 
+    /**
+     * @param expected the expected encoding
+     * @param actual   the actual encoding
+     * @return a new instance of {@link IllegalStateException}.
+     */
     public static IllegalStateException generateWrongEncoding(Encoding expected, Encoding actual) {
         return new IllegalStateException("Cannot visit message as " + expected + " because the actual encoding is " + actual);
     }

core/src/main/java/io/cloudevents/core/provider/CloudEventValidatorProvider.java

@@ -0,0 +1,57 @@
+/*
+ * Copyright 2018-Present The CloudEvents Authors
+ * <p>
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * <p>
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * <p>
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+package io.cloudevents.core.provider;
+
+import io.cloudevents.CloudEvent;
+import io.cloudevents.core.validator.CloudEventValidator;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.ServiceLoader;
+
+/**
+ * CloudEventValidatorProvider is a singleton class which loads and access CE Validator service providers on behalf of service clients.
+ */
+public class CloudEventValidatorProvider {
+
+    private static final CloudEventValidatorProvider cloudEventValidatorProvider = new CloudEventValidatorProvider();
+
+    private final Collection<CloudEventValidator> validators;
+
+    private CloudEventValidatorProvider() {
+        final ServiceLoader<CloudEventValidator> loader = ServiceLoader.load(CloudEventValidator.class);
+        this.validators = new ArrayList<>(2);
+        for (CloudEventValidator cloudEventValidator : loader) {
+            validators.add(cloudEventValidator);
+        }
+    }
+
+    public static CloudEventValidatorProvider getInstance() {
+        return cloudEventValidatorProvider;
+    }
+
+    /**
+     * iterates through available Cloudevent validators.
+     *
+     * @param cloudEvent event to validate.
+     */
+    public void validate(CloudEvent cloudEvent) {
+        for (final CloudEventValidator validator : validators) {
+            validator.validate(cloudEvent);
+        }
+    }
+}

core/src/main/java/io/cloudevents/core/provider/EventFormatProvider.java

@@ -17,70 +17,96 @@
 
 package io.cloudevents.core.provider;
 
+import java.util.HashMap;
+import java.util.ServiceLoader;
+import java.util.Set;
+import java.util.TreeSet;
+import java.util.stream.StreamSupport;
+
+import javax.annotation.ParametersAreNonnullByDefault;
+
+import io.cloudevents.core.format.ContentType;
 import io.cloudevents.core.format.EventFormat;
 import io.cloudevents.lang.Nullable;
 
-import javax.annotation.ParametersAreNonnullByDefault;
-import java.util.HashMap;
-import java.util.ServiceLoader;
-import java.util.stream.StreamSupport;
-
 /**
- * Singleton holding the discovered {@link EventFormat} implementations through {@link ServiceLoader}.
+ * Singleton holding the discovered {@link EventFormat} implementations through
+ * {@link ServiceLoader}.
  * <p>
- * You can resolve an event format using {@code EventFormatProvider.getInstance().resolveFormat(contentType)}.
+ * You can resolve an event format using
+ * {@code EventFormatProvider.getInstance().resolveFormat(contentType)}.
  * <p>
- * You can programmatically add a new {@link EventFormat} implementation using {@link #registerFormat(EventFormat)}.
+ * You can programmatically add a new {@link EventFormat} implementation using
+ * {@link #registerFormat(EventFormat)}.
  */
 @ParametersAreNonnullByDefault
 public final class EventFormatProvider {
 
-    private static class SingletonContainer {
-        private final static EventFormatProvider INSTANCE = new EventFormatProvider();
-    }
+	private static class SingletonContainer {
+		private final static EventFormatProvider INSTANCE = new EventFormatProvider();
+	}
 
-    /**
-     * @return instance of {@link EventFormatProvider}
-     */
-    public static EventFormatProvider getInstance() {
-        return EventFormatProvider.SingletonContainer.INSTANCE;
-    }
+	/**
+	 * @return instance of {@link EventFormatProvider}
+	 */
+	public static EventFormatProvider getInstance() {
+		return EventFormatProvider.SingletonContainer.INSTANCE;
+	}
 
-    private final HashMap<String, EventFormat> formats;
+	private final HashMap<String, EventFormat> formats;
 
-    private EventFormatProvider() {
-        this.formats = new HashMap<>();
+	private EventFormatProvider() {
+		this.formats = new HashMap<>();
 
-        StreamSupport.stream(
-            ServiceLoader.load(EventFormat.class).spliterator(),
-            false
-        ).forEach(this::registerFormat);
-    }
+		StreamSupport.stream(ServiceLoader.load(EventFormat.class).spliterator(), false)
+				.forEach(this::registerFormat);
+	}
 
-    /**
-     * Register a new {@link EventFormat} programmatically.
-     *
-     * @param format the new format to register
-     */
-    public void registerFormat(EventFormat format) {
-        for (String k : format.deserializableContentTypes()) {
-            this.formats.put(k, format);
-        }
-    }
+	/**
+	 * Register a new {@link EventFormat} programmatically.
+	 *
+	 * @param format the new format to register
+	 */
+	public void registerFormat(EventFormat format) {
+		for (String k : format.deserializableContentTypes()) {
+			this.formats.put(k, format);
+		}
+	}
 
-    /**
-     * Resolve an event format starting from the content type.
-     *
-     * @param contentType the content type to resolve the event format
-     * @return null if no format was found for the provided content type
-     */
-    @Nullable
-    public EventFormat resolveFormat(String contentType) {
-        int i = contentType.indexOf(';');
-        if (i != -1) {
-            contentType = contentType.substring(0, i);
-        }
-        return this.formats.get(contentType);
-    }
+	/**
+	 * Enumerate the supported content types.
+	 * 
+	 * @return an alphabetically sorted list of content types
+	 */
+	public Set<String> getContentTypes() {
+		Set<String> types = new TreeSet<>();
+		types.addAll(this.formats.keySet());
+		return types;
+	}
 
+	/**
+	 * Resolve an event format starting from the content type.
+	 *
+	 * @param contentType the content type to resolve the event format
+	 * @return null if no format was found for the provided content type
+	 */
+	@Nullable
+	public EventFormat resolveFormat(String contentType) {
+		int i = contentType.indexOf(';');
+		if (i != -1) {
+			contentType = contentType.substring(0, i);
+		}
+		return this.formats.get(contentType);
+	}
+
+	/**
+	 * Resolve an event format starting from the content type.
+	 *
+	 * @param contentType the content type to resolve the event format
+	 * @return null if no format was found for the provided content type
+	 */
+	@Nullable
+	public EventFormat resolveFormat(ContentType contentType) {
+		return this.formats.get(contentType.value());
+	}
 }

core/src/main/java/io/cloudevents/core/provider/ExtensionProvider.java

@@ -18,7 +18,7 @@
 package io.cloudevents.core.provider;
 
 import io.cloudevents.CloudEventExtensions;
-import io.cloudevents.Extension;
+import io.cloudevents.CloudEventExtension;
 import io.cloudevents.core.extensions.DatarefExtension;
 import io.cloudevents.core.extensions.DistributedTracingExtension;
 import io.cloudevents.lang.Nullable;
@@ -30,7 +30,7 @@ import java.util.function.Supplier;
 /**
  * Singleton to materialize CloudEvent extensions as POJOs.
  * <p>
- * You can materialize an {@link Extension} POJO with {@code ExtensionProvider.getInstance().parseExtension(DistributedTracingExtension.class, event)}.
+ * You can materialize an {@link CloudEventExtension} POJO with {@code ExtensionProvider.getInstance().parseExtension(DistributedTracingExtension.class, event)}.
  */
 @ParametersAreNonnullByDefault
 public final class ExtensionProvider {
@@ -39,6 +39,9 @@ public final class ExtensionProvider {
         private static final ExtensionProvider INSTANCE = new ExtensionProvider();
     }
 
+    /**
+     * @return instance of {@link ExtensionProvider}
+     */
     public static ExtensionProvider getInstance() {
         return SingletonContainer.INSTANCE;
     }
@@ -55,27 +58,28 @@ public final class ExtensionProvider {
     /**
      * Register a new extension type.
      *
-     * @param extensionClass the class implementing {@link Extension}
-     * @param factory the empty arguments factory
-     * @param <T> the type of the extension
+     * @param <T>            the type of the extension
+     * @param extensionClass the class implementing {@link CloudEventExtension}
+     * @param factory        the empty arguments factory
      */
-    public <T extends Extension> void registerExtension(Class<T> extensionClass, Supplier<T> factory) {
+    public <T extends CloudEventExtension> void registerExtension(Class<T> extensionClass, Supplier<T> factory) {
         this.extensionFactories.put(extensionClass, factory);
     }
 
     /**
      * Parse an extension from the {@link CloudEventExtensions}, materializing the corresponding POJO.
      *
-     * @param extensionClass  the class implementing {@link Extension}
-     * @param eventExtensions the event extensions to read
      * @param <T>             the type of the extension
+     * @param extensionClass  the class implementing {@link CloudEventExtension}
+     * @param eventExtensions the event extensions to read
+     * @return the parsed extension
      */
     @SuppressWarnings("unchecked")
     @Nullable
-    public <T extends Extension> T parseExtension(Class<T> extensionClass, CloudEventExtensions eventExtensions) {
+    public <T extends CloudEventExtension> T parseExtension(Class<T> extensionClass, CloudEventExtensions eventExtensions) {
         Supplier<?> factory = extensionFactories.get(extensionClass);
         if (factory != null) {
-            Extension ext = (Extension) factory.get();
+            CloudEventExtension ext = (CloudEventExtension) factory.get();
             ext.readFrom(eventExtensions);
             return (T) ext;
         }

core/src/main/java/io/cloudevents/core/v03/CloudEventBuilder.java

@@ -16,16 +16,22 @@
  */
 package io.cloudevents.core.v03;
 
+import io.cloudevents.CloudEvent;
+import io.cloudevents.SpecVersion;
+import io.cloudevents.core.CloudEventUtils;
+import io.cloudevents.core.impl.BaseCloudEventBuilder;
+import io.cloudevents.core.provider.CloudEventValidatorProvider;
+import io.cloudevents.core.v1.CloudEventV1;
+import io.cloudevents.rw.CloudEventContextReader;
+import io.cloudevents.rw.CloudEventContextWriter;
+import io.cloudevents.rw.CloudEventRWException;
+import io.cloudevents.types.Time;
+
 import java.net.URI;
 import java.net.URISyntaxException;
 import java.time.OffsetDateTime;
 
-import io.cloudevents.SpecVersion;
-import io.cloudevents.core.CloudEventUtils;
-import io.cloudevents.core.impl.BaseCloudEventBuilder;
-import io.cloudevents.rw.CloudEventContextReader;
-import io.cloudevents.rw.CloudEventRWException;
-import io.cloudevents.types.Time;
+import static io.cloudevents.core.v03.CloudEventV03.*;
 
 /**
  * CloudEvent V0.3 builder.
@@ -59,11 +65,10 @@ public final class CloudEventBuilder extends BaseCloudEventBuilder<CloudEventBui
     protected void setAttributes(io.cloudevents.CloudEventContext event) {
         CloudEventContextReader contextReader = CloudEventUtils.toContextReader(event);
         if (event.getSpecVersion() == SpecVersion.V03) {
-            contextReader.readAttributes(this);
+            contextReader.readContext(this);
         } else {
-            contextReader.readAttributes(new V1ToV03AttributesConverter(this));
+            contextReader.readContext(new V1ToV03AttributesConverter(this));
         }
-        contextReader.readExtensions(this);
     }
 
     public CloudEventBuilder withId(String id) {
@@ -119,8 +124,15 @@ public final class CloudEventBuilder extends BaseCloudEventBuilder<CloudEventBui
         if (type == null) {
             throw createMissingAttributeException("type");
         }
+        if (subject != null && subject.isEmpty()) {
+            throw createEmptyAttributeException(("subject"));
+        }
 
-        return new CloudEventV03(id, source, type, time, schemaurl, datacontenttype, subject, this.data, this.extensions);
+        CloudEventV03 cloudEvent = new CloudEventV03(id, source, type, time, schemaurl, datacontenttype, subject, this.data, this.extensions);
+        final CloudEventValidatorProvider validator = CloudEventValidatorProvider.getInstance();
+        validator.validate(cloudEvent);
+
+        return cloudEvent;
     }
 
     @Override
@@ -139,65 +151,166 @@ public final class CloudEventBuilder extends BaseCloudEventBuilder<CloudEventBui
     }
 
     // Message impl
-
     @Override
-    public CloudEventBuilder withAttribute(String name, String value) throws CloudEventRWException {
+    public CloudEventContextWriter withContextAttribute(String name, String value) throws CloudEventRWException {
+        requireValidAttributeWrite(name);
         switch (name) {
-            case "id":
+            case ID:
                 withId(value);
                 return this;
-            case "source":
+            case SOURCE:
                 try {
                     withSource(new URI(value));
                 } catch (URISyntaxException e) {
-                    throw CloudEventRWException.newInvalidAttributeValue("source", value, e);
+                    throw CloudEventRWException.newInvalidAttributeValue(SOURCE, value, e);
                 }
                 return this;
-            case "type":
+            case TYPE:
                 withType(value);
                 return this;
-            case "datacontenttype":
+            case DATACONTENTTYPE:
                 withDataContentType(value);
                 return this;
-            case "datacontentencoding":
+            case DATACONTENTENCODING:
                 // No-op, this information is not saved in the event because it's useful only for parsing
                 return this;
-            case "schemaurl":
+            case SCHEMAURL:
                 try {
                     withSchemaUrl(new URI(value));
                 } catch (URISyntaxException e) {
-                    throw CloudEventRWException.newInvalidAttributeValue("schemaurl", value, e);
+                    throw CloudEventRWException.newInvalidAttributeValue(SCHEMAURL, value, e);
                 }
                 return this;
-            case "subject":
+            case SUBJECT:
                 withSubject(value);
                 return this;
-            case "time":
-                withTime(Time.parseTime("time", value));
+            case TIME:
+                withTime(Time.parseTime(TIME, value));
+                return this;
+            default:
+                withExtension(name, value);
                 return this;
         }
-        throw CloudEventRWException.newInvalidAttributeName(name);
     }
 
     @Override
-    public CloudEventBuilder withAttribute(String name, URI value) throws CloudEventRWException {
+    public CloudEventContextWriter withContextAttribute(String name, URI value) throws CloudEventRWException {
+        requireValidAttributeWrite(name);
         switch (name) {
-            case "source":
+            case SOURCE:
                 withSource(value);
                 return this;
-            case "schemaurl":
+            case SCHEMAURL:
                 withDataSchema(value);
                 return this;
+            case ID:
+            case TYPE:
+            case DATACONTENTTYPE:
+            case DATACONTENTENCODING:
+            case SUBJECT:
+            case TIME:
+                throw CloudEventRWException.newInvalidAttributeType(name, URI.class);
+            default:
+                withExtension(name, value);
+                return this;
         }
-        throw CloudEventRWException.newInvalidAttributeType(name, URI.class);
     }
 
     @Override
-    public CloudEventBuilder withAttribute(String name, OffsetDateTime value) throws CloudEventRWException {
-        if ("time".equals(name)) {
-            withTime(value);
-            return this;
+    public CloudEventContextWriter withContextAttribute(String name, OffsetDateTime value) throws CloudEventRWException {
+        requireValidAttributeWrite(name);
+        switch (name) {
+            case TIME:
+                withTime(value);
+                return this;
+            case SCHEMAURL:
+            case ID:
+            case TYPE:
+            case DATACONTENTTYPE:
+            case DATACONTENTENCODING:
+            case SUBJECT:
+            case SOURCE:
+                throw CloudEventRWException.newInvalidAttributeType(name, OffsetDateTime.class);
+            default:
+                withExtension(name, value);
+                return this;
+        }
+    }
+
+    @Override
+    public CloudEventContextWriter withContextAttribute(String name, Number value) throws CloudEventRWException {
+        requireValidAttributeWrite(name);
+        switch (name) {
+            case TIME:
+            case SCHEMAURL:
+            case ID:
+            case TYPE:
+            case DATACONTENTTYPE:
+            case DATACONTENTENCODING:
+            case SUBJECT:
+            case SOURCE:
+                throw CloudEventRWException.newInvalidAttributeType(name, Number.class);
+            default:
+                withExtension(name, value);
+                return this;
+        }
+    }
+
+    @Override
+    public CloudEventContextWriter withContextAttribute(String name, Integer value) throws CloudEventRWException
+    {
+        requireValidAttributeWrite(name);
+        switch (name) {
+            case TIME:
+            case SCHEMAURL:
+            case ID:
+            case TYPE:
+            case DATACONTENTTYPE:
+            case DATACONTENTENCODING:
+            case SUBJECT:
+            case SOURCE:
+                throw CloudEventRWException.newInvalidAttributeType(name, Integer.class);
+            default:
+                withExtension(name, value);
+                return this;
+        }
+    }
+
+    @Override
+    public CloudEventContextWriter withContextAttribute(String name, Boolean value) throws CloudEventRWException {
+        requireValidAttributeWrite(name);
+        switch (name) {
+            case TIME:
+            case SCHEMAURL:
+            case ID:
+            case TYPE:
+            case DATACONTENTTYPE:
+            case DATACONTENTENCODING:
+            case SUBJECT:
+            case SOURCE:
+                throw CloudEventRWException.newInvalidAttributeType(name, Boolean.class);
+            default:
+                withExtension(name, value);
+                return this;
+        }
+    }
+
+    @Override
+    public CloudEventContextWriter withContextAttribute(String name, byte[] value) throws CloudEventRWException {
+        requireValidAttributeWrite(name);
+        switch (name) {
+            case TIME:
+            case SCHEMAURL:
+            case ID:
+            case TYPE:
+            case DATACONTENTTYPE:
+            case DATACONTENTENCODING:
+            case SUBJECT:
+            case SOURCE:
+                throw CloudEventRWException.newInvalidAttributeType(name, byte[].class);
+            default:
+                withExtension(name, value);
+                return this;
         }
-        throw CloudEventRWException.newInvalidAttributeType(name, OffsetDateTime.class);
     }
 }

core/src/main/java/io/cloudevents/core/v03/CloudEventV03.java

@@ -20,7 +20,7 @@ import io.cloudevents.CloudEventData;
 import io.cloudevents.SpecVersion;
 import io.cloudevents.core.impl.BaseCloudEvent;
 import io.cloudevents.lang.Nullable;
-import io.cloudevents.rw.CloudEventAttributesWriter;
+import io.cloudevents.rw.CloudEventContextWriter;
 import io.cloudevents.rw.CloudEventRWException;
 
 import java.net.URI;
@@ -169,43 +169,44 @@ public final class CloudEventV03 extends BaseCloudEvent {
     }
 
     @Override
-    public void readAttributes(CloudEventAttributesWriter writer) throws CloudEventRWException {
-        writer.withAttribute(
+    public void readContext(CloudEventContextWriter writer) throws CloudEventRWException {
+        writer.withContextAttribute(
             ID,
             this.id
         );
-        writer.withAttribute(
+        writer.withContextAttribute(
             SOURCE,
             this.source
         );
-        writer.withAttribute(
+        writer.withContextAttribute(
             TYPE,
             this.type
         );
         if (this.datacontenttype != null) {
-            writer.withAttribute(
+            writer.withContextAttribute(
                 DATACONTENTTYPE,
                 this.datacontenttype
             );
         }
         if (this.schemaurl != null) {
-            writer.withAttribute(
+            writer.withContextAttribute(
                 SCHEMAURL,
                 this.schemaurl
             );
         }
         if (this.subject != null) {
-            writer.withAttribute(
+            writer.withContextAttribute(
                 SUBJECT,
                 this.subject
             );
         }
         if (this.time != null) {
-            writer.withAttribute(
+            writer.withContextAttribute(
                 TIME,
                 this.time
             );
         }
+        this.readExtensions(writer);
     }
 
     @Override
@@ -235,12 +236,12 @@ public final class CloudEventV03 extends BaseCloudEvent {
             "id='" + id + '\'' +
             ", source=" + source +
             ", type='" + type + '\'' +
-            ", datacontenttype='" + datacontenttype + '\'' +
-            ", schemaurl=" + schemaurl +
-            ", subject='" + subject + '\'' +
-            ", time=" + time +
-            ", data=" + getData() +
-            ", extensions" + this.extensions +
+            ((datacontenttype != null) ? ", datacontenttype='" + datacontenttype + '\'' : "") +
+            ((schemaurl != null) ? ", schemaurl=" + schemaurl : "") +
+            ((subject != null) ? ", subject='" + subject + '\'' : "") +
+            ((time != null) ? ", time=" + time : "") +
+            ((getData() != null) ? ", data=" + getData() : "") +
+            ", extensions=" + this.extensions +
             '}';
     }
 }

core/src/main/java/io/cloudevents/core/v03/V1ToV03AttributesConverter.java

@@ -17,7 +17,7 @@
 
 package io.cloudevents.core.v03;
 
-import io.cloudevents.rw.CloudEventAttributesWriter;
+import io.cloudevents.rw.CloudEventContextWriter;
 import io.cloudevents.rw.CloudEventRWException;
 import io.cloudevents.types.Time;
 
@@ -25,7 +25,9 @@ import java.net.URI;
 import java.net.URISyntaxException;
 import java.time.OffsetDateTime;
 
-class V1ToV03AttributesConverter implements CloudEventAttributesWriter {
+import static io.cloudevents.core.v1.CloudEventV1.*;
+
+class V1ToV03AttributesConverter implements CloudEventContextWriter {
 
     private final CloudEventBuilder builder;
 
@@ -34,60 +36,114 @@ class V1ToV03AttributesConverter implements CloudEventAttributesWriter {
     }
 
     @Override
-    public V1ToV03AttributesConverter withAttribute(String name, String value) throws CloudEventRWException {
+    public CloudEventContextWriter withContextAttribute(String name, String value) throws CloudEventRWException {
         switch (name) {
-            case "id":
+            case ID:
                 builder.withId(value);
                 return this;
-            case "source":
+            case SOURCE:
                 try {
                     builder.withSource(new URI(value));
                 } catch (URISyntaxException e) {
-                    throw CloudEventRWException.newInvalidAttributeValue("source", value, e);
+                    throw CloudEventRWException.newInvalidAttributeValue(SOURCE, value, e);
                 }
                 return this;
-            case "type":
+            case TYPE:
                 builder.withType(value);
                 return this;
-            case "datacontenttype":
+            case DATACONTENTTYPE:
                 builder.withDataContentType(value);
                 return this;
-            case "dataschema":
+            case DATASCHEMA:
                 try {
                     builder.withSchemaUrl(new URI(value));
                 } catch (URISyntaxException e) {
-                    throw CloudEventRWException.newInvalidAttributeValue("dataschema", value, e);
+                    throw CloudEventRWException.newInvalidAttributeValue(DATASCHEMA, value, e);
                 }
                 return this;
-            case "subject":
+            case SUBJECT:
                 builder.withSubject(value);
                 return this;
-            case "time":
-                builder.withTime(Time.parseTime("time", value));
+            case TIME:
+                builder.withTime(Time.parseTime(TIME, value));
+                return this;
+            default:
+                builder.withExtension(name, value);
                 return this;
         }
-        throw CloudEventRWException.newInvalidAttributeName(name);
     }
 
     @Override
-    public V1ToV03AttributesConverter withAttribute(String name, URI value) throws CloudEventRWException {
+    public CloudEventContextWriter withContextAttribute(String name, URI value) throws CloudEventRWException {
         switch (name) {
-            case "source":
+            case SOURCE:
                 builder.withSource(value);
                 return this;
-            case "dataschema":
+            case DATASCHEMA:
                 builder.withSchemaUrl(value);
                 return this;
+            case ID:
+            case TYPE:
+            case DATACONTENTTYPE:
+            case SUBJECT:
+            case TIME:
+                throw CloudEventRWException.newInvalidAttributeType(name, URI.class);
+            default:
+                builder.withExtension(name, value);
+                return this;
         }
-        throw CloudEventRWException.newInvalidAttributeType(name, URI.class);
     }
 
     @Override
-    public V1ToV03AttributesConverter withAttribute(String name, OffsetDateTime value) throws CloudEventRWException {
-        if ("time".equals(name)) {
-            builder.withTime(value);
-            return this;
+    public CloudEventContextWriter withContextAttribute(String name, OffsetDateTime value) throws CloudEventRWException {
+        switch (name) {
+            case TIME:
+                builder.withTime(value);
+                return this;
+            case SOURCE:
+            case DATASCHEMA:
+            case ID:
+            case TYPE:
+            case DATACONTENTTYPE:
+            case SUBJECT:
+                throw CloudEventRWException.newInvalidAttributeType(name, OffsetDateTime.class);
+            default:
+                builder.withExtension(name, value);
+                return this;
+        }
+    }
+
+    @Override
+    public CloudEventContextWriter withContextAttribute(String name, Number value) throws CloudEventRWException {
+        switch (name) {
+            case TIME:
+            case SOURCE:
+            case DATASCHEMA:
+            case ID:
+            case TYPE:
+            case DATACONTENTTYPE:
+            case SUBJECT:
+                throw CloudEventRWException.newInvalidAttributeType(name, Number.class);
+            default:
+                builder.withExtension(name, value);
+                return this;
+        }
+    }
+
+    @Override
+    public CloudEventContextWriter withContextAttribute(String name, Boolean value) throws CloudEventRWException {
+        switch (name) {
+            case TIME:
+            case SOURCE:
+            case DATASCHEMA:
+            case ID:
+            case TYPE:
+            case DATACONTENTTYPE:
+            case SUBJECT:
+                throw CloudEventRWException.newInvalidAttributeType(name, Boolean.class);
+            default:
+                builder.withExtension(name, value);
+                return this;
         }
-        throw CloudEventRWException.newInvalidAttributeType(name, OffsetDateTime.class);
     }
 }

core/src/main/java/io/cloudevents/core/v1/CloudEventBuilder.java

@@ -21,7 +21,10 @@ import io.cloudevents.CloudEvent;
 import io.cloudevents.SpecVersion;
 import io.cloudevents.core.CloudEventUtils;
 import io.cloudevents.core.impl.BaseCloudEventBuilder;
+import io.cloudevents.core.provider.CloudEventValidatorProvider;
+import io.cloudevents.core.validator.CloudEventValidator;
 import io.cloudevents.rw.CloudEventContextReader;
+import io.cloudevents.rw.CloudEventContextWriter;
 import io.cloudevents.rw.CloudEventRWException;
 import io.cloudevents.types.Time;
 
@@ -29,6 +32,8 @@ import java.net.URI;
 import java.net.URISyntaxException;
 import java.time.OffsetDateTime;
 
+import static io.cloudevents.core.v1.CloudEventV1.*;
+
 /**
  * CloudEvent V1.0 builder.
  *
@@ -61,11 +66,10 @@ public final class CloudEventBuilder extends BaseCloudEventBuilder<CloudEventBui
     protected void setAttributes(io.cloudevents.CloudEventContext event) {
         CloudEventContextReader contextReader = CloudEventUtils.toContextReader(event);
         if (event.getSpecVersion() == SpecVersion.V1) {
-            contextReader.readAttributes(this);
+            contextReader.readContext(this);
         } else {
-            contextReader.readAttributes(new V03ToV1AttributesConverter(this));
+            contextReader.readContext(new V03ToV1AttributesConverter(this));
         }
-        contextReader.readExtensions(this);
     }
 
     public CloudEventBuilder withId(String id) {
@@ -108,16 +112,24 @@ public final class CloudEventBuilder extends BaseCloudEventBuilder<CloudEventBui
     @Override
     public CloudEvent build() {
         if (id == null) {
-            throw createMissingAttributeException(CloudEventV1.ID);
+            throw createMissingAttributeException(ID);
         }
         if (source == null) {
-            throw createMissingAttributeException(CloudEventV1.SOURCE);
+            throw createMissingAttributeException(SOURCE);
         }
         if (type == null) {
-            throw createMissingAttributeException(CloudEventV1.TYPE);
+            throw createMissingAttributeException(TYPE);
+        }
+        if (subject != null && subject.isEmpty()) {
+            throw createEmptyAttributeException(("subject"));
         }
 
-        return new CloudEventV1(id, source, type, datacontenttype, dataschema, subject, time, this.data, this.extensions);
+        CloudEvent cloudEvent = new CloudEventV1(id, source, type, datacontenttype, dataschema, subject, time, this.data, this.extensions);
+
+        final CloudEventValidatorProvider validator = CloudEventValidatorProvider.getInstance();
+        validator.validate(cloudEvent);
+
+        return cloudEvent;
     }
 
     @Override
@@ -138,60 +150,157 @@ public final class CloudEventBuilder extends BaseCloudEventBuilder<CloudEventBui
     // Message impl
 
     @Override
-    public CloudEventBuilder withAttribute(String name, String value) throws CloudEventRWException {
+    public CloudEventContextWriter withContextAttribute(String name, String value) throws CloudEventRWException {
+        requireValidAttributeWrite(name);
         switch (name) {
-            case CloudEventV1.ID:
+            case ID:
                 withId(value);
                 return this;
-            case CloudEventV1.SOURCE:
+            case SOURCE:
                 try {
                     withSource(new URI(value));
                 } catch (URISyntaxException e) {
-                    throw CloudEventRWException.newInvalidAttributeValue(CloudEventV1.SOURCE, value, e);
+                    throw CloudEventRWException.newInvalidAttributeValue(SOURCE, value, e);
                 }
                 return this;
-            case CloudEventV1.TYPE:
+            case TYPE:
                 withType(value);
                 return this;
-            case CloudEventV1.DATACONTENTTYPE:
+            case DATACONTENTTYPE:
                 withDataContentType(value);
                 return this;
-            case CloudEventV1.DATASCHEMA:
+            case DATASCHEMA:
                 try {
                     withDataSchema(new URI(value));
                 } catch (URISyntaxException e) {
-                    throw CloudEventRWException.newInvalidAttributeValue(CloudEventV1.DATASCHEMA, value, e);
+                    throw CloudEventRWException.newInvalidAttributeValue(DATASCHEMA, value, e);
                 }
                 return this;
-            case CloudEventV1.SUBJECT:
+            case SUBJECT:
                 withSubject(value);
                 return this;
-            case CloudEventV1.TIME:
-                withTime(Time.parseTime(CloudEventV1.TIME, value));
+            case TIME:
+                withTime(Time.parseTime(TIME, value));
+                return this;
+            default:
+                withExtension(name, value);
                 return this;
         }
-        throw CloudEventRWException.newInvalidAttributeName(name);
     }
 
     @Override
-    public CloudEventBuilder withAttribute(String name, URI value) throws CloudEventRWException {
+    public CloudEventContextWriter withContextAttribute(String name, URI value) throws CloudEventRWException {
+        requireValidAttributeWrite(name);
         switch (name) {
-            case CloudEventV1.SOURCE:
+            case SOURCE:
                 withSource(value);
                 return this;
-            case CloudEventV1.DATASCHEMA:
+            case DATASCHEMA:
                 withDataSchema(value);
                 return this;
+            case ID:
+            case TYPE:
+            case DATACONTENTTYPE:
+            case SUBJECT:
+            case TIME:
+                throw CloudEventRWException.newInvalidAttributeType(name, URI.class);
+            default:
+                withExtension(name, value);
+                return this;
         }
-        throw CloudEventRWException.newInvalidAttributeType(name, URI.class);
     }
 
     @Override
-    public CloudEventBuilder withAttribute(String name, OffsetDateTime value) throws CloudEventRWException {
-        if (CloudEventV1.TIME.equals(name)) {
-            withTime(value);
-            return this;
+    public CloudEventContextWriter withContextAttribute(String name, OffsetDateTime value) throws CloudEventRWException {
+        requireValidAttributeWrite(name);
+        switch (name) {
+            case TIME:
+                withTime(value);
+                return this;
+            case DATASCHEMA:
+            case ID:
+            case TYPE:
+            case DATACONTENTTYPE:
+            case SUBJECT:
+            case SOURCE:
+                throw CloudEventRWException.newInvalidAttributeType(name, OffsetDateTime.class);
+            default:
+                withExtension(name, value);
+                return this;
+        }
+    }
+
+    @Override
+    public CloudEventContextWriter withContextAttribute(String name, Number value) throws CloudEventRWException {
+        requireValidAttributeWrite(name);
+        switch (name) {
+            case TIME:
+            case DATASCHEMA:
+            case ID:
+            case TYPE:
+            case DATACONTENTTYPE:
+            case SUBJECT:
+            case SOURCE:
+                throw CloudEventRWException.newInvalidAttributeType(name, Number.class);
+            default:
+                withExtension(name, value);
+                return this;
+        }
+    }
+
+    @Override
+    public CloudEventContextWriter withContextAttribute(String name, Integer value) throws CloudEventRWException
+    {
+        requireValidAttributeWrite(name);
+        switch (name) {
+            case TIME:
+            case DATASCHEMA:
+            case ID:
+            case TYPE:
+            case DATACONTENTTYPE:
+            case SUBJECT:
+            case SOURCE:
+                throw CloudEventRWException.newInvalidAttributeType(name, Integer.class);
+            default:
+                withExtension(name, value);
+                return this;
+        }
+    }
+
+    @Override
+    public CloudEventContextWriter withContextAttribute(String name, Boolean value) throws CloudEventRWException {
+        requireValidAttributeWrite(name);
+        switch (name) {
+            case TIME:
+            case DATASCHEMA:
+            case ID:
+            case TYPE:
+            case DATACONTENTTYPE:
+            case SUBJECT:
+            case SOURCE:
+                throw CloudEventRWException.newInvalidAttributeType(name, Boolean.class);
+            default:
+                withExtension(name, value);
+                return this;
+        }
+    }
+
+    @Override
+    public CloudEventContextWriter withContextAttribute(String name, byte[] value)
+        throws CloudEventRWException {
+        requireValidAttributeWrite(name);
+        switch (name) {
+            case TIME:
+            case DATASCHEMA:
+            case ID:
+            case TYPE:
+            case DATACONTENTTYPE:
+            case SUBJECT:
+            case SOURCE:
+                throw CloudEventRWException.newInvalidAttributeType(name, byte[].class);
+            default:
+                withExtension(name, value);
+                return this;
         }
-        throw CloudEventRWException.newInvalidAttributeType(name, OffsetDateTime.class);
     }
 }

core/src/main/java/io/cloudevents/core/v1/CloudEventV1.java

@@ -19,7 +19,7 @@ package io.cloudevents.core.v1;
 import io.cloudevents.CloudEventData;
 import io.cloudevents.SpecVersion;
 import io.cloudevents.core.impl.BaseCloudEvent;
-import io.cloudevents.rw.CloudEventAttributesWriter;
+import io.cloudevents.rw.CloudEventContextWriter;
 import io.cloudevents.rw.CloudEventRWException;
 
 import java.net.URI;
@@ -156,43 +156,44 @@ public final class CloudEventV1 extends BaseCloudEvent {
     }
 
     @Override
-    public void readAttributes(CloudEventAttributesWriter writer) throws CloudEventRWException {
-        writer.withAttribute(
+    public void readContext(CloudEventContextWriter writer) throws CloudEventRWException {
+        writer.withContextAttribute(
             ID,
             this.id
         );
-        writer.withAttribute(
+        writer.withContextAttribute(
             SOURCE,
             this.source
         );
-        writer.withAttribute(
+        writer.withContextAttribute(
             TYPE,
             this.type
         );
         if (this.datacontenttype != null) {
-            writer.withAttribute(
+            writer.withContextAttribute(
                 DATACONTENTTYPE,
                 this.datacontenttype
             );
         }
         if (this.dataschema != null) {
-            writer.withAttribute(
+            writer.withContextAttribute(
                 DATASCHEMA,
                 this.dataschema
             );
         }
         if (this.subject != null) {
-            writer.withAttribute(
+            writer.withContextAttribute(
                 SUBJECT,
                 this.subject
             );
         }
         if (this.time != null) {
-            writer.withAttribute(
+            writer.withContextAttribute(
                 TIME,
                 this.time
             );
         }
+        this.readExtensions(writer);
     }
 
     @Override
@@ -222,11 +223,11 @@ public final class CloudEventV1 extends BaseCloudEvent {
             "id='" + id + '\'' +
             ", source=" + source +
             ", type='" + type + '\'' +
-            ", datacontenttype='" + datacontenttype + '\'' +
-            ", dataschema=" + dataschema +
-            ", subject='" + subject + '\'' +
-            ", time=" + time +
-            ", data=" + getData() +
+            ((datacontenttype != null) ? ", datacontenttype='" + datacontenttype + '\'' : "") +
+            ((dataschema != null) ? ", dataschema=" + dataschema : "") +
+            ((subject != null) ? ", subject='" + subject + '\'' : "") +
+            ((time != null) ? ", time=" + time : "") +
+            ((getData() != null) ? ", data=" + getData() : "") +
             ", extensions=" + this.extensions +
             '}';
     }

core/src/main/java/io/cloudevents/core/v1/V03ToV1AttributesConverter.java

@@ -17,7 +17,7 @@
 
 package io.cloudevents.core.v1;
 
-import io.cloudevents.rw.CloudEventAttributesWriter;
+import io.cloudevents.rw.CloudEventContextWriter;
 import io.cloudevents.rw.CloudEventRWException;
 import io.cloudevents.types.Time;
 
@@ -25,7 +25,9 @@ import java.net.URI;
 import java.net.URISyntaxException;
 import java.time.OffsetDateTime;
 
-class V03ToV1AttributesConverter implements CloudEventAttributesWriter {
+import static io.cloudevents.core.v03.CloudEventV03.*;
+
+class V03ToV1AttributesConverter implements CloudEventContextWriter {
 
     private final CloudEventBuilder builder;
 
@@ -34,60 +36,114 @@ class V03ToV1AttributesConverter implements CloudEventAttributesWriter {
     }
 
     @Override
-    public V03ToV1AttributesConverter withAttribute(String name, String value) throws CloudEventRWException {
+    public CloudEventContextWriter withContextAttribute(String name, String value) throws CloudEventRWException {
         switch (name) {
-            case "id":
+            case ID:
                 builder.withId(value);
                 return this;
-            case "source":
+            case SOURCE:
                 try {
                     builder.withSource(new URI(value));
                 } catch (URISyntaxException e) {
-                    throw CloudEventRWException.newInvalidAttributeValue("source", value, e);
+                    throw CloudEventRWException.newInvalidAttributeValue(SOURCE, value, e);
                 }
                 return this;
-            case "type":
+            case TYPE:
                 builder.withType(value);
                 return this;
-            case "datacontenttype":
+            case DATACONTENTTYPE:
                 builder.withDataContentType(value);
                 return this;
-            case "schemaurl":
+            case SCHEMAURL:
                 try {
                     builder.withDataSchema(new URI(value));
                 } catch (URISyntaxException e) {
-                    throw CloudEventRWException.newInvalidAttributeValue("dataschema", value, e);
+                    throw CloudEventRWException.newInvalidAttributeValue(SCHEMAURL, value, e);
                 }
                 return this;
-            case "subject":
+            case SUBJECT:
                 builder.withSubject(value);
                 return this;
-            case "time":
-                builder.withTime(Time.parseTime("time", value));
+            case TIME:
+                builder.withTime(Time.parseTime(TIME, value));
+                return this;
+            default:
+                builder.withExtension(name, value);
                 return this;
         }
-        throw CloudEventRWException.newInvalidAttributeName(name);
     }
 
     @Override
-    public V03ToV1AttributesConverter withAttribute(String name, URI value) throws CloudEventRWException {
+    public CloudEventContextWriter withContextAttribute(String name, URI value) throws CloudEventRWException {
         switch (name) {
-            case "source":
+            case SOURCE:
                 builder.withSource(value);
                 return this;
-            case "schemaurl":
+            case SCHEMAURL:
                 builder.withDataSchema(value);
                 return this;
+            case ID:
+            case TYPE:
+            case DATACONTENTTYPE:
+            case SUBJECT:
+            case TIME:
+                throw CloudEventRWException.newInvalidAttributeType(name, URI.class);
+            default:
+                builder.withExtension(name, value);
+                return this;
         }
-        throw CloudEventRWException.newInvalidAttributeType(name, URI.class);
     }
 
     @Override
-    public V03ToV1AttributesConverter withAttribute(String name, OffsetDateTime value) throws CloudEventRWException {
-        if ("time".equals(name)) {
-            builder.withTime(value);
-            return this;
+    public CloudEventContextWriter withContextAttribute(String name, OffsetDateTime value) throws CloudEventRWException {
+        switch (name) {
+            case TIME:
+                builder.withTime(value);
+                return this;
+            case SOURCE:
+            case SCHEMAURL:
+            case ID:
+            case TYPE:
+            case DATACONTENTTYPE:
+            case SUBJECT:
+                throw CloudEventRWException.newInvalidAttributeType(name, OffsetDateTime.class);
+            default:
+                builder.withExtension(name, value);
+                return this;
+        }
+    }
+
+    @Override
+    public CloudEventContextWriter withContextAttribute(String name, Number value) throws CloudEventRWException {
+        switch (name) {
+            case TIME:
+            case SOURCE:
+            case SCHEMAURL:
+            case ID:
+            case TYPE:
+            case DATACONTENTTYPE:
+            case SUBJECT:
+                throw CloudEventRWException.newInvalidAttributeType(name, Number.class);
+            default:
+                builder.withExtension(name, value);
+                return this;
+        }
+    }
+
+    @Override
+    public CloudEventContextWriter withContextAttribute(String name, Boolean value) throws CloudEventRWException {
+        switch (name) {
+            case TIME:
+            case SOURCE:
+            case SCHEMAURL:
+            case ID:
+            case TYPE:
+            case DATACONTENTTYPE:
+            case SUBJECT:
+                throw CloudEventRWException.newInvalidAttributeType(name, Boolean.class);
+            default:
+                builder.withExtension(name, value);
+                return this;
         }
-        throw CloudEventRWException.newInvalidAttributeType(name, OffsetDateTime.class);
     }
 }

core/src/main/java/io/cloudevents/core/validator/CloudEventValidator.java

@@ -14,15 +14,20 @@
  * limitations under the License.
  *
  */
-
-package io.cloudevents.http.restful.ws.impl;
+package io.cloudevents.core.validator;
 
 import io.cloudevents.CloudEvent;
 
-public class Utils {
-
-    public static boolean isCloudEventEntity(Object obj) {
-        return obj != null && CloudEvent.class.isAssignableFrom(obj.getClass());
-    }
+/**
+ * @author Vinay Bhat
+ * Interface which defines validation for CloudEvents attributes and extensions.
+ */
+public interface CloudEventValidator {
 
+    /**
+     * Validate the attributes of a CloudEvent.
+     *
+     * @param cloudEvent the CloudEvent to validate
+     */
+    void validate(CloudEvent cloudEvent);
 }

core/src/test/java/io/cloudevents/core/data/PojoCloudEventDataTest.java

@@ -1,5 +1,7 @@
 package io.cloudevents.core.data;
 
+import java.nio.charset.StandardCharsets;
+
 import org.junit.jupiter.api.Test;
 
 import static org.assertj.core.api.Assertions.assertThat;
@@ -8,7 +10,7 @@ class PojoCloudEventDataTest {
 
     @Test
     void testWrapAndMemoization() {
-        PojoCloudEventData<Integer> data = PojoCloudEventData.wrap(10, i -> i.toString().getBytes());
+        PojoCloudEventData<Integer> data = PojoCloudEventData.wrap(10, i -> i.toString().getBytes(StandardCharsets.UTF_8));
 
         assertThat(data.getValue())
             .isEqualTo(10);
@@ -16,7 +18,7 @@ class PojoCloudEventDataTest {
         byte[] firstConversion = data.toBytes();
 
         assertThat(firstConversion)
-            .isEqualTo("10".getBytes());
+            .isEqualTo("10".getBytes(StandardCharsets.UTF_8));
 
         assertThat(data.toBytes())
             .isSameAs(firstConversion);
@@ -24,7 +26,7 @@ class PojoCloudEventDataTest {
 
     @Test
     void testAlreadySerializedValue() {
-        byte[] serialized = "10".getBytes();
+        byte[] serialized = "10".getBytes(StandardCharsets.UTF_8);
         PojoCloudEventData<Integer> data = PojoCloudEventData.wrap(10, v -> serialized);
 
         assertThat(data.getValue())

core/src/test/java/io/cloudevents/core/impl/BaseCloudEventBuilderTest.java

@@ -1,15 +1,16 @@
 package io.cloudevents.core.impl;
 
-import static org.assertj.core.api.Assertions.assertThat;
-import static org.junit.jupiter.api.Assertions.assertThrows;
-import static org.junit.jupiter.api.Assertions.assertTrue;
-
-import org.junit.jupiter.api.Test;
-
 import io.cloudevents.CloudEvent;
 import io.cloudevents.core.builder.CloudEventBuilder;
 import io.cloudevents.core.extensions.DistributedTracingExtension;
 import io.cloudevents.core.test.Data;
+import org.junit.jupiter.api.Test;
+
+import java.util.Objects;
+
+import static io.cloudevents.core.test.Data.*;
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.junit.jupiter.api.Assertions.*;
 
 public class BaseCloudEventBuilderTest {
 
@@ -49,17 +50,23 @@ public class BaseCloudEventBuilderTest {
     }
 
     @Test
-    public void testLongExtensionName() {
-        Exception exception = assertThrows(RuntimeException.class, () -> {
-            CloudEvent cloudEvent = CloudEventBuilder.v1(Data.V1_WITH_JSON_DATA_WITH_EXT)
+    public void testLongExtensionNameV1() {
+        assertDoesNotThrow(() -> {
+            CloudEventBuilder.v1(Data.V1_WITH_JSON_DATA_WITH_EXT)
                 .withExtension("thisextensionnameistoolong", "")
                 .build();
         });
-        String expectedMessage = "Invalid extensions name: thisextensionnameistoolong";
-        String actualMessage = exception.getMessage();
-
-        assertTrue(actualMessage.contains(expectedMessage));
     }
+
+    @Test
+    public void testLongExtensionNameV03() {
+        assertDoesNotThrow(() -> {
+            CloudEventBuilder.v03(Data.V1_WITH_JSON_DATA_WITH_EXT)
+                .withExtension("thisextensionnameistoolong", "")
+                .build();
+        });
+    }
+
     @Test
     public void testInvalidExtensionName() {
         Exception exception = assertThrows(RuntimeException.class, () -> {
@@ -72,4 +79,64 @@ public class BaseCloudEventBuilderTest {
 
         assertTrue(actualMessage.contains(expectedMessage));
     }
+
+    @Test
+    public void testBinaryExtension() {
+
+        final String EXT_NAME = "verifyme";
+
+        CloudEvent given = CloudEventBuilder.v1(Data.V1_MIN)
+            .withExtension(EXT_NAME, Data.BINARY_VALUE)
+            .build();
+
+        // Sanity
+        assertNotNull(given);
+
+        // Did the extension stick
+        assertTrue(given.getExtensionNames().contains(EXT_NAME));
+        assertNotNull(given.getExtension(EXT_NAME));
+
+        // Does the extension have the right value
+        assertEquals(Data.BINARY_VALUE, given.getExtension(EXT_NAME));
+
+    }
+
+    @Test
+    public void withoutDataRemovesDataAttributeFromCopiedCloudEvent() {
+        CloudEvent original = CloudEventBuilder.v1(Data.V1_WITH_JSON_DATA_WITH_EXT).build();
+        CloudEvent copy = CloudEventBuilder.v1(original).withoutData().build();
+
+        assertAll(
+            () -> assertThat(copy.getData()).isNull(),
+            () -> assertThat(copy.getDataContentType()).isEqualTo(DATACONTENTTYPE_JSON),
+            () -> assertThat(copy.getDataSchema()).isEqualTo(DATASCHEMA)
+        );
+
+    }
+
+    @Test
+    public void withoutDataContentTypeRemovesDataContentTypeAttributeFromCopiedCloudEvent() {
+        CloudEvent original = CloudEventBuilder.v1(Data.V1_WITH_JSON_DATA_WITH_EXT).build();
+        CloudEvent copy = CloudEventBuilder.v1(original).withoutDataContentType().build();
+
+        assertAll(
+            () -> assertThat(Objects.requireNonNull(copy.getData()).toBytes()).isEqualTo(DATA_JSON_SERIALIZED),
+            () -> assertThat(copy.getDataContentType()).isNull(),
+            () -> assertThat(copy.getDataSchema()).isEqualTo(DATASCHEMA)
+        );
+
+    }
+
+    @Test
+    public void withoutDataSchemaRemovesDataSchemaAttributeFromCopiedCloudEvent() {
+        CloudEvent original = CloudEventBuilder.v1(Data.V1_WITH_JSON_DATA_WITH_EXT).build();
+        CloudEvent copy = CloudEventBuilder.v1(original).withoutDataSchema().build();
+
+        assertAll(
+            () -> assertThat(Objects.requireNonNull(copy.getData()).toBytes()).isEqualTo(DATA_JSON_SERIALIZED),
+            () -> assertThat(copy.getDataContentType()).isEqualTo(DATACONTENTTYPE_JSON),
+            () -> assertThat(copy.getDataSchema()).isNull()
+        );
+
+    }
 }

core/src/test/java/io/cloudevents/core/impl/CloudEventImplTest.java

@@ -91,4 +91,28 @@ public class CloudEventImplTest {
             );
     }
 
+    @Test
+    public void testToStringV1() {
+        CloudEvent event = CloudEventBuilder.v1()
+            .withId(ID)
+            .withType(TYPE)
+            .withSource(SOURCE)
+            .build();
+
+        assertThat(event.toString())
+            .doesNotContain("time");
+    }
+
+    @Test
+    public void testToStringV03() {
+        CloudEvent event = CloudEventBuilder.v03()
+            .withId(ID)
+            .withType(TYPE)
+            .withSource(SOURCE)
+            .build();
+
+        assertThat(event.toString())
+            .doesNotContain("time");
+    }
+
 }

core/src/test/java/io/cloudevents/core/impl/StringUtilsTest.java

@@ -0,0 +1,44 @@
+/*
+ * Copyright 2018-Present The CloudEvents Authors
+ * <p>
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * <p>
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * <p>
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package io.cloudevents.core.impl;
+
+import org.assertj.core.api.Assertions;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.Arguments;
+import org.junit.jupiter.params.provider.MethodSource;
+
+import java.util.stream.Stream;
+
+public class StringUtilsTest {
+
+    @ParameterizedTest
+    @MethodSource("startsWithIgnoreCaseArgs")
+    public void startsWithIgnoreCase(final String s, final String prefix, final boolean expected) {
+        Assertions.assertThat(StringUtils.startsWithIgnoreCase(s, prefix)).isEqualTo(expected);
+    }
+
+    private static Stream<Arguments> startsWithIgnoreCaseArgs() {
+        return Stream.of(
+            Arguments.of("s", "s", true),
+            Arguments.of("sa", "S", true),
+            Arguments.of("saS", "As", false),
+            Arguments.of("sasso", "SASO", false),
+            Arguments.of("sasso", "SaSsO", true)
+        );
+    }
+}

core/src/test/java/io/cloudevents/core/message/impl/MessageUtilsTest.java

@@ -27,6 +27,25 @@ class MessageUtilsTest {
             .isEqualTo(CloudEventRWException.CloudEventRWExceptionKind.UNKNOWN_ENCODING);
     }
 
+
+    /**
+     * Verify an exception is thrown if an unsupported
+     * application/cloudevents content-type family is
+     * received.
+     */
+    @ParameterizedTest
+    @MethodSource
+    void testBadContentTypes(String contentType) {
+
+        CloudEventRWException exception = assertThrows(CloudEventRWException.class, () ->
+        {
+            parseStructuredOrBinaryMessage(() -> contentType, eventFormat -> null, () -> "1.0", specVersion -> null);
+        });
+
+        assertThat(exception.getKind()).isEqualTo(CloudEventRWException.CloudEventRWExceptionKind.UNKNOWN_ENCODING);
+
+    }
+
     @Test
     void testParseStructuredOrBinaryMessage_StructuredMode() {
         MessageUtils.parseStructuredOrBinaryMessage(() -> "application/cloudevents+csv;",
@@ -54,4 +73,11 @@ class MessageUtilsTest {
         );
     }
 
+    private static Stream<Arguments> testBadContentTypes() {
+        return Stream.of(
+            Arguments.of("application/cloudevents"),
+            Arguments.of("application/cloudevents+morse")
+        );
+    }
+
 }

core/src/test/java/io/cloudevents/core/mock/CSVFormat.java

@@ -55,7 +55,7 @@ public class CSVFormat implements EventFormat {
             event.getData() != null
                 ? new String(Base64.getEncoder().encode(event.getData().toBytes()), StandardCharsets.UTF_8)
                 : "null"
-        ).getBytes();
+        ).getBytes(StandardCharsets.UTF_8);
     }
 
     @Override
@@ -70,7 +70,7 @@ public class CSVFormat implements EventFormat {
         URI dataschema = splitted[5].equals("null") ? null : URI.create(splitted[5]);
         String subject = splitted[6].equals("null") ? null : splitted[6];
         OffsetDateTime time = splitted[7].equals("null") ? null : Time.parseTime(splitted[7]);
-        byte[] data = splitted[8].equals("null") ? null : Base64.getDecoder().decode(splitted[8].getBytes());
+        byte[] data = splitted[8].equals("null") ? null : Base64.getDecoder().decode(splitted[8].getBytes(StandardCharsets.UTF_8));
 
         CloudEventBuilder builder = CloudEventBuilder.fromSpecVersion(sv)
             .withId(id)

core/src/test/java/io/cloudevents/core/mock/MockBinaryMessageWriter.java

@@ -34,24 +34,21 @@ import java.util.Map;
 public class MockBinaryMessageWriter extends BaseBinaryMessageReader implements MessageReader, CloudEventContextReader, CloudEventWriterFactory<MockBinaryMessageWriter, MockBinaryMessageWriter>, CloudEventWriter<MockBinaryMessageWriter> {
 
     private SpecVersion version;
-    private Map<String, Object> attributes;
+    private Map<String, Object> context;
     private CloudEventData data;
-    private Map<String, Object> extensions;
 
-    public MockBinaryMessageWriter(SpecVersion version, Map<String, Object> attributes, CloudEventData data, Map<String, Object> extensions) {
+    public MockBinaryMessageWriter(SpecVersion version, Map<String, Object> context, CloudEventData data) {
         this.version = version;
-        this.attributes = attributes;
+        this.context = context;
         this.data = data;
-        this.extensions = extensions;
     }
 
-    public MockBinaryMessageWriter(SpecVersion version, Map<String, Object> attributes, byte[] data, Map<String, Object> extensions) {
-        this(version, attributes, BytesCloudEventData.wrap(data), extensions);
+    public MockBinaryMessageWriter(SpecVersion version, Map<String, Object> context, byte[] data) {
+        this(version, context, BytesCloudEventData.wrap(data));
     }
 
     public MockBinaryMessageWriter() {
-        this.attributes = new HashMap<>();
-        this.extensions = new HashMap<>();
+        this.context = new HashMap<>();
     }
 
     public MockBinaryMessageWriter(CloudEvent event) {
@@ -67,47 +64,14 @@ public class MockBinaryMessageWriter extends BaseBinaryMessageReader implements
             throw new IllegalStateException("MockBinaryMessage is empty");
         }
 
-        CloudEventWriter<V> visitor = writerFactory.create(version);
-        this.readAttributes(visitor);
-        this.readExtensions(visitor);
+        CloudEventWriter<V> writer = writerFactory.create(version);
+        this.readContext(writer);
 
         if (this.data != null) {
-            return visitor.end(mapper.map(this.data));
+            return writer.end(mapper.map(this.data));
         }
 
-        return visitor.end();
-    }
-
-    @Override
-    public void readAttributes(CloudEventAttributesWriter writer) throws CloudEventRWException, IllegalStateException {
-        for (Map.Entry<String, Object> e : this.attributes.entrySet()) {
-            if (e.getValue() instanceof String) {
-                writer.withAttribute(e.getKey(), (String) e.getValue());
-            } else if (e.getValue() instanceof OffsetDateTime) {
-                writer.withAttribute(e.getKey(), (OffsetDateTime) e.getValue());
-            } else if (e.getValue() instanceof URI) {
-                writer.withAttribute(e.getKey(), (URI) e.getValue());
-            } else {
-                // This should never happen because we build that map only through our builders
-                throw new IllegalStateException("Illegal value inside attributes map: " + e);
-            }
-        }
-    }
-
-    @Override
-    public void readExtensions(CloudEventExtensionsWriter writer) throws CloudEventRWException, IllegalStateException {
-        for (Map.Entry<String, Object> entry : this.extensions.entrySet()) {
-            if (entry.getValue() instanceof String) {
-                writer.withExtension(entry.getKey(), (String) entry.getValue());
-            } else if (entry.getValue() instanceof Number) {
-                writer.withExtension(entry.getKey(), (Number) entry.getValue());
-            } else if (entry.getValue() instanceof Boolean) {
-                writer.withExtension(entry.getKey(), (Boolean) entry.getValue());
-            } else {
-                // This should never happen because we build that map only through our builders
-                throw new IllegalStateException("Illegal value inside extensions map: " + entry);
-            }
-        }
+        return writer.end();
     }
 
     @Override
@@ -121,46 +85,60 @@ public class MockBinaryMessageWriter extends BaseBinaryMessageReader implements
         return this;
     }
 
-    @Override
-    public MockBinaryMessageWriter withAttribute(String name, String value) throws CloudEventRWException {
-        this.attributes.put(name, value);
-        return this;
-    }
-
-    @Override
-    public MockBinaryMessageWriter withAttribute(String name, URI value) throws CloudEventRWException {
-        this.attributes.put(name, value);
-        return this;
-    }
-
-    @Override
-    public MockBinaryMessageWriter withAttribute(String name, OffsetDateTime value) throws CloudEventRWException {
-        this.attributes.put(name, value);
-        return this;
-    }
-
-    @Override
-    public MockBinaryMessageWriter withExtension(String name, String value) throws CloudEventRWException {
-        this.extensions.put(name, value);
-        return this;
-    }
-
-    @Override
-    public MockBinaryMessageWriter withExtension(String name, Number value) throws CloudEventRWException {
-        this.extensions.put(name, value);
-        return this;
-    }
-
-    @Override
-    public MockBinaryMessageWriter withExtension(String name, Boolean value) throws CloudEventRWException {
-        this.extensions.put(name, value);
-        return this;
-    }
-
     @Override
     public MockBinaryMessageWriter create(SpecVersion version) {
         this.version = version;
 
         return this;
     }
+
+    @Override
+    public void readContext(CloudEventContextWriter writer) throws CloudEventRWException {
+        for (Map.Entry<String, Object> entry : this.context.entrySet()) {
+            if (entry.getValue() instanceof String) {
+                writer.withContextAttribute(entry.getKey(), (String) entry.getValue());
+            } else if (entry.getValue() instanceof OffsetDateTime) {
+                writer.withContextAttribute(entry.getKey(), (OffsetDateTime) entry.getValue());
+            } else if (entry.getValue() instanceof URI) {
+                writer.withContextAttribute(entry.getKey(), (URI) entry.getValue());
+            } else if (entry.getValue() instanceof Number) {
+                writer.withContextAttribute(entry.getKey(), (Number) entry.getValue());
+            } else if (entry.getValue() instanceof Boolean) {
+                writer.withContextAttribute(entry.getKey(), (Boolean) entry.getValue());
+            } else {
+                // This should never happen because we build that map only through our builders
+                throw new IllegalStateException("Illegal value inside context map: " + entry);
+            }
+        }
+    }
+
+    @Override
+    public CloudEventContextWriter withContextAttribute(String name, String value) throws CloudEventRWException {
+        this.context.put(name, value);
+        return this;
+    }
+
+    @Override
+    public CloudEventContextWriter withContextAttribute(String name, URI value) throws CloudEventRWException {
+        this.context.put(name, value);
+        return this;
+    }
+
+    @Override
+    public CloudEventContextWriter withContextAttribute(String name, OffsetDateTime value) throws CloudEventRWException {
+        this.context.put(name, value);
+        return this;
+    }
+
+    @Override
+    public CloudEventContextWriter withContextAttribute(String name, Number value) throws CloudEventRWException {
+        this.context.put(name, value);
+        return this;
+    }
+
+    @Override
+    public CloudEventContextWriter withContextAttribute(String name, Boolean value) throws CloudEventRWException {
+        this.context.put(name, value);
+        return this;
+    }
 }

core/src/test/java/io/cloudevents/core/mock/MockStructuredMessageReader.java

@@ -41,12 +41,12 @@ public class MockStructuredMessageReader extends BaseStructuredMessageReader imp
     }
 
     @Override
-    public <T> T read(StructuredMessageWriter<T> visitor) throws CloudEventRWException, IllegalStateException {
+    public <T> T read(StructuredMessageWriter<T> writer) throws CloudEventRWException, IllegalStateException {
         if (this.format == null) {
             throw new IllegalStateException("MockStructuredMessage is empty");
         }
 
-        return visitor.setEvent(this.format, this.payload);
+        return writer.setEvent(this.format, this.payload);
     }
 
     @Override

core/src/test/java/io/cloudevents/core/mock/MyCloudEventData.java

@@ -1,7 +1,7 @@
 package io.cloudevents.core.mock;
 
 import io.cloudevents.CloudEventData;
-
+import java.nio.charset.StandardCharsets;
 import java.util.Objects;
 
 public class MyCloudEventData implements CloudEventData {
@@ -14,7 +14,7 @@ public class MyCloudEventData implements CloudEventData {
 
     @Override
     public byte[] toBytes() {
-        return Integer.toString(value).getBytes();
+        return Integer.toString(value).getBytes(StandardCharsets.UTF_8);
     }
 
     public int getValue() {

core/src/test/java/io/cloudevents/core/provider/EventFormatProviderTest.java

@@ -36,4 +36,9 @@ public class EventFormatProviderTest {
             .isInstanceOf(CSVFormat.class);
     }
 
+    @Test
+    void listTypes() {
+        assertThat(EventFormatProvider.getInstance().getContentTypes()).hasSize(1);
+    }
+
 }

core/src/test/java/io/cloudevents/core/test/CloudEventCustomValidator.java

@@ -0,0 +1,17 @@
+package io.cloudevents.core.test;
+
+import io.cloudevents.CloudEvent;
+import io.cloudevents.core.validator.CloudEventValidator;
+
+public class CloudEventCustomValidator implements CloudEventValidator {
+
+    @Override
+    public void validate(CloudEvent cloudEvent) {
+        String namespace = null;
+        if ((namespace = (String) cloudEvent.getExtension("namespace")) != null &&
+            !namespace.equals("sales")){
+            throw new IllegalStateException("Expecting sales in namespace extension");
+        }
+    }
+
+}

core/src/test/java/io/cloudevents/core/test/Data.java

@@ -21,7 +21,9 @@ import io.cloudevents.CloudEvent;
 import io.cloudevents.core.builder.CloudEventBuilder;
 import io.cloudevents.types.Time;
 
+import java.math.BigDecimal;
 import java.net.URI;
+import java.nio.charset.StandardCharsets;
 import java.time.OffsetDateTime;
 import java.util.Objects;
 import java.util.stream.Stream;
@@ -38,9 +40,10 @@ public class Data {
     public static final String SUBJECT = "sub";
     public static final OffsetDateTime TIME = Time.parseTime("2018-04-26T14:48:09+02:00");
 
-    public static byte[] DATA_JSON_SERIALIZED = "{}".getBytes();
-    public static byte[] DATA_XML_SERIALIZED = "<stuff></stuff>".getBytes();
-    public static byte[] DATA_TEXT_SERIALIZED = "Hello World Lorena!".getBytes();
+    public static byte[] DATA_JSON_SERIALIZED = "{}".getBytes(StandardCharsets.UTF_8);
+    public static byte[] DATA_XML_SERIALIZED = "<stuff></stuff>".getBytes(StandardCharsets.UTF_8);
+    public static byte[] DATA_TEXT_SERIALIZED = "Hello World Lorena!".getBytes(StandardCharsets.UTF_8);
+    public static byte[] BINARY_VALUE = { (byte) 0xE0, (byte) 0xFF, (byte) 0x00, (byte) 0x44, (byte) 0xAA }; // Base64: 4P8ARKo=
 
     public static final CloudEvent V1_MIN = CloudEventBuilder.v1()
         .withId(ID)
@@ -108,6 +111,23 @@ public class Data {
         .withTime(TIME)
         .build();
 
+    public static final CloudEvent V1_WITH_BINARY_EXT = CloudEventBuilder.v1()
+        .withId(ID)
+        .withType(TYPE)
+        .withSource(SOURCE)
+        .withExtension("binary", BINARY_VALUE)
+        .build();
+
+    public static final CloudEvent V1_WITH_NUMERIC_EXT = CloudEventBuilder.v1()
+        .withId(ID)
+        .withType(TYPE)
+        .withSource(SOURCE)
+        .withExtension("integer", 42)
+        .withExtension("decimal", new BigDecimal("42.42"))
+        .withExtension("float", 4.2f)
+        .withExtension("long", new Long(4200))
+        .build();
+
     public static final CloudEvent V03_MIN = CloudEventBuilder.v03(V1_MIN).build();
     public static final CloudEvent V03_WITH_JSON_DATA = CloudEventBuilder.v03(V1_WITH_JSON_DATA).build();
     public static final CloudEvent V03_WITH_JSON_DATA_WITH_EXT = CloudEventBuilder.v03(V1_WITH_JSON_DATA_WITH_EXT).build();
@@ -137,6 +157,18 @@ public class Data {
         );
     }
 
+    /**
+     * Due to the nature of CE there are scenarios where an event might be serialized
+     * in such a fashion that it can not be deserialized while retaining the orginal
+     * type information, this varies from format-2-format
+     */
+
+    public static Stream<CloudEvent> v1NonRoundTripEvents() {
+        return Stream.of(
+            Data.V1_WITH_BINARY_EXT
+        );
+    }
+
     public static Stream<CloudEvent> v03Events() {
         return Stream.of(
             Data.V03_MIN,

core/src/test/java/io/cloudevents/core/v03/CloudEventBuilderTest.java

@@ -158,4 +158,27 @@ public class CloudEventBuilderTest {
         ).hasMessageContaining("Attribute 'type' cannot be null");
     }
 
+    @Test
+    void testMissingSubject() {
+        CloudEvent actual = CloudEventBuilder
+            .v03()
+            .withId("000")
+            .withSource(URI.create("http://localhost"))
+            .withType(TYPE)
+            .build();
+
+        assertThat(actual).isNotNull();
+    }
+
+    @Test
+    void testEmptySubject() {
+        assertThatCode(() -> CloudEventBuilder
+            .v03()
+            .withId("000")
+            .withSource(URI.create("http://localhost"))
+            .withType(TYPE)
+            .withSubject("")
+            .build()
+        ).hasMessageContaining("Attribute 'subject' cannot be empty");
+    }
 }

core/src/test/java/io/cloudevents/core/v1/CloudEventBuilderTest.java

@@ -142,4 +142,39 @@ public class CloudEventBuilderTest {
         ).hasMessageContaining("Attribute 'type' cannot be null");
     }
 
+    @Test
+    void testValidatorProvider(){
+        assertThatCode(() -> CloudEventBuilder
+            .v1()
+            .withId("000")
+            .withSource(URI.create("http://localhost"))
+            .withType(TYPE)
+            .withExtension("namespace", "order")
+            .build()
+        ).hasMessageContaining("Expecting sales in namespace extension");
+    }
+
+    @Test
+    void testMissingSubject() {
+        CloudEvent actual = CloudEventBuilder
+            .v1()
+            .withId("000")
+            .withSource(URI.create("http://localhost"))
+            .withType(TYPE)
+            .build();
+
+        assertThat(actual).isNotNull();
+    }
+
+    @Test
+    void testEmptySubject() {
+        assertThatCode(() -> CloudEventBuilder
+            .v1()
+            .withId("000")
+            .withSource(URI.create("http://localhost"))
+            .withType(TYPE)
+            .withSubject("")
+            .build()
+        ).hasMessageContaining("Attribute 'subject' cannot be empty");
+    }
 }

core/src/test/resources/META-INF/services/io.cloudevents.core.validator.CloudEventValidator

@@ -0,0 +1 @@
+io.cloudevents.core.test.CloudEventCustomValidator

docs/Gemfile.lock

@@ -1,14 +1,14 @@
 GEM
   remote: https://rubygems.org/
   specs:
-    activesupport (6.0.3.4)
+    activesupport (6.0.6.1)
       concurrent-ruby (~> 1.0, >= 1.0.2)
       i18n (>= 0.7, < 2)
       minitest (~> 5.1)
       tzinfo (~> 1.1)
       zeitwerk (~> 2.2, >= 2.2.2)
-    addressable (2.7.0)
-      public_suffix (>= 2.0.2, < 5.0)
+    addressable (2.8.1)
+      public_suffix (>= 2.0.2, < 6.0)
     coffee-script (2.4.1)
       coffee-script-source
       execjs
@@ -16,7 +16,7 @@ GEM
     colorator (1.1.0)
     commonmarker (0.17.13)
       ruby-enum (~> 0.5)
-    concurrent-ruby (1.1.7)
+    concurrent-ruby (1.2.0)
     dnsruby (1.61.5)
       simpleidn (~> 0.1)
     em-websocket (0.5.2)
@@ -82,7 +82,7 @@ GEM
       octokit (~> 4.0)
       public_suffix (~> 3.0)
       typhoeus (~> 1.3)
-    html-pipeline (2.14.0)
+    html-pipeline (2.14.3)
       activesupport (>= 2)
       nokogiri (>= 1.4)
     http_parser.rb (0.6.0)
@@ -203,30 +203,32 @@ GEM
     kramdown-parser-gfm (1.1.0)
       kramdown (~> 2.0)
     liquid (4.0.3)
-    listen (3.3.0)
+    listen (3.7.1)
       rb-fsevent (~> 0.10, >= 0.10.3)
       rb-inotify (~> 0.9, >= 0.9.10)
     mercenary (0.3.6)
-    mini_portile2 (2.4.0)
+    mini_portile2 (2.8.8)
     minima (2.5.1)
       jekyll (>= 3.5, < 5.0)
       jekyll-feed (~> 0.9)
       jekyll-seo-tag (~> 2.1)
-    minitest (5.14.2)
+    minitest (5.17.0)
     multipart-post (2.1.1)
-    nokogiri (1.10.10)
-      mini_portile2 (~> 2.4.0)
+    nokogiri (1.18.3)
+      mini_portile2 (~> 2.8.2)
+      racc (~> 1.4)
     octokit (4.19.0)
       faraday (>= 0.9)
       sawyer (~> 0.8.0, >= 0.5.3)
     pathutil (0.16.2)
       forwardable-extended (~> 2.6)
     public_suffix (3.1.1)
+    racc (1.8.1)
     rake (13.0.1)
     rb-fsevent (0.10.4)
     rb-inotify (0.10.1)
       ffi (~> 1.0)
-    rexml (3.2.4)
+    rexml (3.3.9)
     rouge (3.23.0)
     ruby-enum (0.8.0)
       i18n
@@ -248,13 +250,13 @@ GEM
     thread_safe (0.3.6)
     typhoeus (1.4.0)
       ethon (>= 0.9.0)
-    tzinfo (1.2.8)
+    tzinfo (1.2.11)
       thread_safe (~> 0.1)
     unf (0.1.4)
       unf_ext
     unf_ext (0.0.7.7)
     unicode-display_width (1.7.0)
-    zeitwerk (2.4.1)
+    zeitwerk (2.6.6)
 
 PLATFORMS
   ruby

docs/_config.yml

@@ -4,19 +4,19 @@
 title: Java SDK for CloudEvents
 remote_theme: pmarsceill/just-the-docs
 plugins:
-  - jemoji
+    - jemoji
 
 search_enabled: true
 
 gh_edit_link: true
 gh_edit_link_text: "Edit this page on GitHub."
 gh_edit_repository: "https://github.com/cloudevents/sdk-java"
-gh_edit_branch: "master"
+gh_edit_branch: "main"
 gh_edit_source: docs
 gh_edit_view_mode: "tree"
 
 aux_links:
-  "GitHub Repository":
-    - "https://github.com/cloudevents/sdk-java"
-  "CloudEvents home":
-    - "https://cloudevents.io/"
+    "GitHub Repository":
+        - "https://github.com/cloudevents/sdk-java"
+    "CloudEvents home":
+        - "https://cloudevents.io/"

docs/amqp-proton.md

@@ -0,0 +1,47 @@
+---
+title: CloudEvents AMQP Proton
+nav_order: 5
+---
+
+# CloudEvents AMQP Proton
+
+[![Javadocs](http://www.javadoc.io/badge/io.cloudevents/cloudevents-amqp-proton.svg?color=green)](http://www.javadoc.io/doc/io.cloudevents/cloudevents-amqp-proton)
+
+This module implements `MessageReader` and `MessageWriter` using the Qpid Proton
+library. It can be used with Qpid Proton or any integrations based on Qpid
+Proton (e.g vertx-proton).
+
+For Maven based projects, use the following to configure the `proton` AMQP
+binding for CloudEvents:
+
+```xml
+<dependency>
+    <groupId>io.cloudevents</groupId>
+    <artifactId>cloudevents-amqp-proton</artifactId>
+    <version>4.0.1</version>
+</dependency>
+```
+
+## Sending and Receiving CloudEvents
+
+To send and receive CloudEvents we use `MessageWriter` and `MessageReader`,
+respectively. This module offers factory methods for creation of those in
+`ProtonAmqpMessageFactory`.
+
+```java
+public class ProtonAmqpMessageFactory {
+    public static MessageReader createReader(final Message message);
+
+    public static MessageReader createReader(final String contentType, final ApplicationProperties props, @Nullable final Section body);
+
+    public static MessageWriter createWriter();
+}
+```
+
+## Examples:
+
+The example uses the `vertx-proton` integration to send/receive CloudEvent
+messages over AMQP:
+
+-   [Vertx AmqpServer](https://github.com/cloudevents/sdk-java/tree/main/examples/amqp-proton/src/main/java/io/cloudevents/examples/amqp/vertx/AmqpServer.java)
+-   [Vertx AmqpClient](https://github.com/cloudevents/sdk-java/tree/main/examples/amqp-proton/src/main/java/io/cloudevents/examples/amqp/vertx/AmqpClient.java)

docs/api.md

@@ -0,0 +1,65 @@
+---
+title: CloudEvents API
+nav_order: 2
+---
+
+# CloudEvents API
+
+[![Javadocs](http://www.javadoc.io/badge/io.cloudevents/cloudevents-api.svg?color=green)](http://www.javadoc.io/doc/io.cloudevents/cloudevents-api)
+
+This module contains the interfaces to represent `CloudEvent` in memory and to
+read and write an object using as CloudEvent.
+
+For Maven based projects, use the following dependency:
+
+```xml
+
+<dependency>
+    <groupId>io.cloudevents</groupId>
+    <artifactId>cloudevents-api</artifactId>
+    <version>4.0.1</version>
+</dependency>
+```
+
+## `CloudEvent` hierarchy
+
+`CloudEvent` is the main interface representing a read-only CloudEvent in-memory
+representation. A `CloudEvent` is composed by its context attributes, including
+the predefined attributes and the extensions, and the data.
+
+![](api.png)
+
+`CloudEventData` is an abstraction to allow carrying any kind of data payload
+inside a `CloudEvent`, while enforcing the ability of convert such data to
+`[]byte`, ultimately used to send `CloudEvent` on the wire.
+
+## Reader and Writer
+
+The package `io.cloudevents.rw` contains the interfaces to read and write
+objects as CloudEvents.
+
+![](rw.png)
+
+In other words, you can use these interfaces to perform an unstructured
+read/write of an entity as CloudEvent. For example, an HTTP server request in
+binary mode containing a valid CloudEvent can be translated to a
+`CloudEventReader`. Similarly, an HTTP server response can be written as a
+CloudEvent, hence an eventual response builder could implement
+`CloudEventWriter`.
+
+`CloudEventReader` and `CloudEventWriter` implementations doesn't have any
+particular knowledge about specification version, difference between attributes
+and extensions, and so on. Their only concern is how to read and write context
+attributes and data back and forth to the "CloudEvents type system", as defined
+in the package `io.cloudevents`.
+
+A 3rd party implementer can implement these interfaces directly in its
+`CloudEvent` in order to customize/implement efficiently the
+marshalling/unmarshalling process. These interfaces are optional and, if your
+`CloudEvent` doesn't implement it, a default implementation is provided by the
+core module.
+
+## Other interfaces
+
+- `CloudEventExtension` represents a _materialized_ in-memory representation of a CloudEvent extension
+- `SpecVersion` is an enum of CloudEvents' specification versions supported by this SDK version.

docs/avro.md

@@ -0,0 +1,49 @@
+---
+title: CloudEvents Avro Compact
+nav_order: 4
+---
+
+# CloudEvents Avro Compact
+
+[![Javadocs](http://www.javadoc.io/badge/io.cloudevents/cloudevents-avro-compact.svg?color=green)](http://www.javadoc.io/doc/io.cloudevents/cloudevents-avro-compact)
+
+This module provides the Avro Compact `EventFormat` implementation.
+
+# Setup
+For Maven based projects, use the following dependency:
+
+```xml
+<dependency>
+    <groupId>io.cloudevents</groupId>
+    <artifactId>cloudevents-avro-compact</artifactId>
+    <version>4.0.1</version>
+</dependency>
+```
+
+No further configuration is required is use the module.
+
+## Using the Avro Compact Event Format
+
+### Event serialization
+
+```java
+import io.cloudevents.CloudEvent;
+import io.cloudevents.core.provider.EventFormatProvider;
+import io.cloudevents.core.builder.CloudEventBuilder;
+import io.cloudevents.avro.avro.compact.AvroCompactFormat;
+
+CloudEvent event = CloudEventBuilder.v1()
+    .withId("hello")
+    .withType("example.vertx")
+    .withSource(URI.create("http://localhost"))
+    .build();
+
+byte[] serialized = EventFormatProvider
+    .getInstance()
+    .resolveFormat(AvroCompactFormat.CONTENT_TYPE)
+    .serialize(event);
+```
+
+The `EventFormatProvider` will automatically resolve the format using the
+`ServiceLoader` APIs.
+

docs/core.md

@@ -0,0 +1,115 @@
+---
+title: CloudEvents Core
+nav_order: 3
+---
+
+# CloudEvents Core
+
+[![Javadocs](http://www.javadoc.io/badge/io.cloudevents/cloudevents-core.svg?color=green)](http://www.javadoc.io/doc/io.cloudevents/cloudevents-core)
+
+This package includes implementations and utilities to create and process
+`CloudEvent` and interfaces to deal with Protocol Bindings and Event Formats.
+
+For Maven based projects, use the following dependency:
+
+```xml
+<dependency>
+    <groupId>io.cloudevents</groupId>
+    <artifactId>cloudevents-core</artifactId>
+    <version>4.0.1</version>
+</dependency>
+```
+
+### Using `CloudEvent`s
+
+To create an event, you can use the `CloudEventBuilder`:
+
+```java
+import io.cloudevents.CloudEvent;
+import io.cloudevents.core.builder.CloudEventBuilder;
+
+import java.net.URI;
+
+final CloudEvent event = CloudEventBuilder.v1()
+    .withId("000")
+    .withType("example.demo")
+    .withSource(URI.create("http://example.com"))
+    .withData("text/plain","Hello world!".getBytes("UTF-8"))
+    .build();
+```
+
+Now you can access the event context attributes and data:
+
+```java
+// Get an event attribute
+String id = event.getId();
+
+// Get an event extension
+Object someExtension = event.getExtension("myextension");
+
+// Retrieve the event data
+CloudEventData data = event.getData();
+```
+
+### Creating and accessing to the event data
+
+`CloudEventData` is an abstraction that can wrap any kind of data payload, while
+still enforcing the conversion to bytes. To convert to bytes:
+
+```java
+// Convert the event data to bytes
+byte[]bytes = cloudEventData.toBytes();
+```
+
+If you want to map the JSON event data to POJOs using Jackson, check out the
+[CloudEvents Jackson documentation](json-jackson.md).
+
+When building an event, you can wrap a POJO inside its payload using
+`PojoCloudEventData`, providing the function to convert it back to bytes:
+
+```java
+CloudEventData pojoData = PojoCloudEventData.wrap(myPojo, myPojo::toBytes);
+```
+
+### Using Event Formats
+
+The SDK implements
+[Event Formats](https://github.com/cloudevents/spec/blob/v1.0/spec.md#event-format)
+in various submodules, but keeping a single entrypoint for users who wants to
+serialize/deserialize events back and forth to event formats.
+
+To use an Event Format, you just need to add the event format implementation you
+prefer as dependency in your project and the core module, through the
+`ServiceLoader` mechanism, will load it into the classpath. For example, to use
+the
+[JSON event format](https://github.com/cloudevents/spec/blob/v1.0/json-format.md)
+with Jackson, add `cloudevents-json-jackson` as a dependency and then using the
+`EventFormatProvider`:
+
+```java
+import io.cloudevents.core.provider.EventFormatProvider;
+import io.cloudevents.jackson.JsonFormat;
+
+EventFormat format = EventFormatProvider
+  .getInstance()
+  .resolveFormat(JsonFormat.CONTENT_TYPE);
+
+// Serialize event
+byte[] serialized = format.serialize(event);
+
+// Deserialize event
+CloudEvent event = format.deserialize(bytes);
+```
+
+### Materialize an Extension
+
+CloudEvent extensions can be materialized in their respective POJOs using the
+`ExtensionProvider`:
+
+```java
+import io.cloudevents.core.extensions.DistributedTracingExtension;
+import io.cloudevents.core.provider.ExtensionProvider;
+
+DistributedTracingExtension dte = ExtensionProvider.getInstance()
+    .parseExtension(DistributedTracingExtension.class, event);
+```

docs/http-basic.md

@@ -0,0 +1,53 @@
+---
+title: CloudEvents HTTP Basic
+nav_order: 5
+---
+
+# Generic HTTP Protocol Binding
+
+[![Javadocs](http://www.javadoc.io/badge/io.cloudevents/cloudevents-http-basic.svg?color=green)](http://www.javadoc.io/doc/io.cloudevents/cloudevents-http-basic)
+
+This module is designed to be usable with various HTTP APIs.
+
+There are also more specialized HTTP bindings:
+
+- [`cloudevents-http-vertx`](http-vertx.md)
+- [`cloudevents-http-restful-ws`](http-jakarta-restful-ws.md)
+- [`cloudevents-spring`](spring.md)
+
+Since this module is generic it doesn't offer optimal performance for all HTTP
+implementations. For better performance consider implementing `MessageReader`
+and `MessageWriter` that are tailored for specific HTTP implementation. As a
+reference you can take aforementioned existing bindings.
+
+For Maven based projects, use the following to configure the CloudEvents Generic
+HTTP Transport:
+
+```xml
+<dependency>
+    <groupId>io.cloudevents</groupId>
+    <artifactId>cloudevents-http-basic</artifactId>
+    <version>4.0.1</version>
+</dependency>
+```
+
+## Sending and Receiving CloudEvents
+
+To send and receive CloudEvents we use `MessageWriter` and `MessageReader`,
+respectively. This module offers factory methods for creation of those in
+`HttpMessageFactory`.
+
+```java
+public class HttpMessageFactory {
+    public static MessageReader createReader(Consumer<BiConsumer<String,String>> forEachHeader, byte[] body);
+    public static MessageReader createReader(Map<String,String> headers, byte[] body);
+    public static MessageReader createReaderFromMultimap(Map<String,List<String>> headers, byte[] body);
+    public static MessageWriter createWriter(BiConsumer<String, String> putHeader, Consumer<byte[]> sendBody);
+}
+```
+
+## Examples
+
+- [Standard Java HttpServer](https://github.com/cloudevents/sdk-java/tree/main/examples/basic-http/src/main/java/io/cloudevents/examples/http/basic/BasicHttpServer.java)
+- [Http Client with HttpURLConnection](https://github.com/cloudevents/sdk-java/tree/main/examples/basic-http/src/main/java/io/cloudevents/examples/http/basic/HttpURLConnectionClient.java)
+- [Http Servlet with Jetty](https://github.com/cloudevents/sdk-java/tree/main/examples/basic-http/src/main/java/io/cloudevents/examples/http/basic/JettyServer.java)

docs/http-jakarta-restful-ws-jakarta.md

@@ -0,0 +1,137 @@
+---
+title: CloudEvents HTTP Jakarta EE 9+ - Jakarta RESTful Web Services
+nav_order: 5
+---
+
+# HTTP Protocol Binding for Jakarta EE 9+ - Jakarta RESTful Web Services
+
+[![Javadocs](https://www.javadoc.io/badge/io.cloudevents/cloudevents-http-restful-ws.svg?color=green)](https://www.javadoc.io/doc/io.cloudevents/cloudevents-http-restful-ws)
+
+For Maven based projects, use the following to configure the CloudEvents Jakarta
+RESTful Web Services Binding for Jakarta EE 9+:
+
+```xml
+<dependency>
+    <groupId>io.cloudevents</groupId>
+    <artifactId>cloudevents-http-restful-ws-jakarta</artifactId>
+    <version>4.0.1</version>
+</dependency>
+```
+
+This integration is tested with Jersey (Requires JDK11 or higher), RestEasy & Microprofile Liberty.
+
+#### * Before using this package ensure your web framework  does support the `jakarta.*` namespace.
+
+## Receiving CloudEvents
+
+You need to configure the `CloudEventsProvider` to enable
+marshalling/unmarshalling of CloudEvents.
+
+Below is a sample on how to read and write CloudEvents:
+
+```java
+import io.cloudevents.CloudEvent;
+import io.cloudevents.core.builder.CloudEventBuilder;
+
+import jakarta.ws.rs.GET;
+import jakarta.ws.rs.POST;
+import jakarta.ws.rs.Path;
+import jakarta.ws.rs.core.Response;
+
+@Path("/")
+public class EventReceiverResource {
+
+
+
+    @GET
+    @Path("getMinEvent")
+    public CloudEvent getMinEvent() {
+        return CloudEventBuilder.v1()
+            .withId("hello")
+            .withType("example.vertx")
+            .withSource(URI.create("http://localhost"))
+            .build();
+    }
+
+    // Return the CloudEvent using the HTTP binding structured encoding
+    @GET
+    @Path("getStructuredEvent")
+    @StructuredEncoding("application/cloudevents+csv")
+    public CloudEvent getStructuredEvent() {
+        return CloudEventBuilder.v1()
+            .withId("hello")
+            .withType("example.vertx")
+            .withSource(URI.create("http://localhost"))
+            .build();
+    }
+
+    @POST
+    @Path("postEventWithoutBody")
+    public Response postEvent(CloudEvent inputEvent) {
+        // Handle the event
+        return Response.ok().build();
+    }
+}
+```
+
+## Sending CloudEvents
+
+You need to configure the `CloudEventsProvider` to enable
+marshalling/unmarshalling of CloudEvents.
+
+Below is a sample on how to use the client to send a CloudEvent:
+
+```java
+import io.cloudevents.CloudEvent;
+import io.cloudevents.http.restful.ws.CloudEventsProvider;
+
+import jakarta.ws.rs.client.Entity;
+import jakarta.ws.rs.client.WebTarget;
+import jakarta.ws.rs.core.HttpHeaders;
+import jakarta.ws.rs.core.Response;
+
+public class CloudEventSender {
+
+    public Response sendEvent(WebTarget target, CloudEvent event) {
+        return target
+            .path("postEvent")
+            .request()
+            .buildPost(Entity.entity(event, CloudEventsProvider.CLOUDEVENT_TYPE))
+            .invoke();
+    }
+
+    public Response sendEventAsStructured(WebTarget target, CloudEvent event) {
+        return target
+            .path("postEvent")
+            .request()
+            .buildPost(Entity.entity(event, "application/cloudevents+json"))
+            .invoke();
+    }
+
+    public CloudEvent getEvent(WebTarget target) {
+        Response response = target
+            .path("getEvent")
+            .request()
+            .buildGet()
+            .invoke();
+
+        return response.readEntity(CloudEvent.class);
+    }
+}
+```
+
+## Migrating EE 8 applications to EE 9+
+The main change between Jakarta EE 8 and Jakarta EE 9 and future versions is the changing of the `javax.` to `jakarta.` namespaces used by key packages such as `jakarta.ws.rs-api` which provides the restful-ws API.
+
+This change largely impacts only `import` statements it does filter down to dependencies such as this.
+
+### Application migration
+For application migration we would recommend reviewing materials available from https://jakarta.ee/resources/#documentation as a starting point.
+
+### CloudEvents Dependency
+To migrate to use EE 9+ supported package - replace `cloudevents-http-restful-ws` with `cloudevents-http-restful-ws-jakarta` and ensure the version is a minimum of `2.5.0-SNAPSHOT`
+
+## Examples
+
+- [Microprofile and Liberty](https://github.com/cloudevents/sdk-java/tree/main/examples/restful-ws-micropofile-liberty)
+

docs/http-jakarta-restful-ws.md

@@ -0,0 +1,122 @@
+---
+title: CloudEvents HTTP Jakarta RESTful Web Services
+nav_order: 5
+---
+
+# HTTP Protocol Binding for Jakarta EE8 - RESTful Web Services
+
+[![Javadocs](http://www.javadoc.io/badge/io.cloudevents/cloudevents-http-restful-ws.svg?color=green)](http://www.javadoc.io/doc/io.cloudevents/cloudevents-http-restful-ws)
+
+For Maven based projects, use the following to configure the CloudEvents Jakarta
+RESTful Web Services Binding for Jakarta EE 8:
+
+```xml
+<dependency>
+    <groupId>io.cloudevents</groupId>
+    <artifactId>cloudevents-http-restful-ws</artifactId>
+    <version>4.0.1</version>
+</dependency>
+```
+
+This integration is tested with Jersey, RestEasy & Spring Boot Jersey.
+
+## Receiving CloudEvents
+
+You need to configure the `CloudEventsProvider` to enable
+marshalling/unmarshalling of CloudEvents.
+
+Below is a sample on how to read and write CloudEvents:
+
+```java
+import io.cloudevents.CloudEvent;
+import io.cloudevents.core.builder.CloudEventBuilder;
+
+import javax.ws.rs.GET;
+import javax.ws.rs.POST;
+import javax.ws.rs.Path;
+import javax.ws.rs.core.Response;
+
+@Path("/")
+public class EventReceiverResource {
+
+    @GET
+    @Path("getMinEvent")
+    public CloudEvent getMinEvent() {
+        return CloudEventBuilder.v1()
+            .withId("hello")
+            .withType("example.vertx")
+            .withSource(URI.create("http://localhost"))
+            .build();
+    }
+
+    // Return the CloudEvent using the HTTP binding structured encoding
+    @GET
+    @Path("getStructuredEvent")
+    @StructuredEncoding("application/cloudevents+csv")
+    public CloudEvent getStructuredEvent() {
+        return CloudEventBuilder.v1()
+            .withId("hello")
+            .withType("example.vertx")
+            .withSource(URI.create("http://localhost"))
+            .build();
+    }
+
+    @POST
+    @Path("postEventWithoutBody")
+    public Response postEvent(CloudEvent inputEvent) {
+        // Handle the event
+        return Response.ok().build();
+    }
+}
+```
+
+## Sending CloudEvents
+
+You need to configure the `CloudEventsProvider` to enable
+marshalling/unmarshalling of CloudEvents.
+
+Below is a sample on how to use the client to send a CloudEvent:
+
+```java
+import io.cloudevents.CloudEvent;
+import io.cloudevents.http.restful.ws.CloudEventsProvider;
+
+import javax.ws.rs.client.Entity;
+import javax.ws.rs.client.WebTarget;
+import javax.ws.rs.core.HttpHeaders;
+import javax.ws.rs.core.Response;
+
+public class CloudEventSender {
+
+    public Response sendEvent(WebTarget target, CloudEvent event) {
+        return target
+            .path("postEvent")
+            .request()
+            .buildPost(Entity.entity(event, CloudEventsProvider.CLOUDEVENT_TYPE))
+            .invoke();
+    }
+
+    public Response sendEventAsStructured(WebTarget target, CloudEvent event) {
+        return target
+            .path("postEvent")
+            .request()
+            .buildPost(Entity.entity(event, "application/cloudevents+json"))
+            .invoke();
+    }
+
+    public CloudEvent getEvent(WebTarget target) {
+        Response response = target
+            .path("getEvent")
+            .request()
+            .buildGet()
+            .invoke();
+
+        return response.readEntity(CloudEvent.class);
+    }
+}
+```
+
+## Examples
+
+- [Quarkus and Resteasy](https://github.com/cloudevents/sdk-java/tree/main/examples/restful-ws-quarkus)
+- [Jersey and Spring Boot](https://github.com/cloudevents/sdk-java/tree/main/examples/restful-ws-spring-boot)

docs/http-vertx.md

@@ -0,0 +1,98 @@
+---
+title: CloudEvents HTTP Vert.x
+nav_order: 5
+---
+
+# HTTP Protocol Binding for Eclipse Vert.x
+
+[![Javadocs](http://www.javadoc.io/badge/io.cloudevents/cloudevents-http-vertx.svg?color=green)](http://www.javadoc.io/doc/io.cloudevents/cloudevents-http-vertx)
+
+For Maven based projects, use the following to configure the CloudEvents Vertx
+HTTP Transport:
+
+```xml
+<dependency>
+    <groupId>io.cloudevents</groupId>
+    <artifactId>cloudevents-http-vertx</artifactId>
+    <version>4.0.1</version>
+</dependency>
+```
+
+## Receiving CloudEvents
+
+Assuming you have in classpath [`cloudevents-json-jackson`](json-jackson.md),
+below is a sample on how to read and write CloudEvents:
+
+```java
+
+import io.cloudevents.http.vertx.VertxMessageFactory;
+import io.cloudevents.core.message.StructuredMessageReader;
+import io.cloudevents.CloudEvent;
+import io.vertx.core.AbstractVerticle;
+
+public class CloudEventServerVerticle extends AbstractVerticle {
+
+  public void start() {
+    vertx.createHttpServer()
+      .requestHandler(req -> {
+        VertxMessageFactory.createReader(req)
+          .onSuccess(messageReader -> {
+            CloudEvent event = messageReader.toEvent();
+            // Echo the message, as structured mode
+            VertxMessageFactory
+              .createWriter(req.response())
+              .writeStructured(event, "application/cloudevents+json");
+          })
+          .onFailure(t -> req.response().setStatusCode(500).end());
+      })
+      .listen(8080)
+      .onSuccess(server ->
+        System.out.println("Server started on port " + server.actualPort())
+      ).onFailure(t -> {
+        System.out.println("Error starting the server");
+        serverResult.cause().printStackTrace();
+      });
+  }
+}
+```
+
+## Sending CloudEvents
+
+Below is a sample on how to use the client to send and receive a CloudEvent:
+
+```java
+import io.cloudevents.CloudEvent;
+import io.cloudevents.core.builder.CloudEventBuilder;
+import io.cloudevents.http.vertx.VertxMessageFactory;
+import io.vertx.core.AbstractVerticle;
+import io.vertx.ext.web.client.WebClient;
+
+import java.net.URI;
+
+public class CloudEventClientVerticle extends AbstractVerticle {
+
+  public void start() {
+    WebClient client = WebClient.create(vertx);
+
+    CloudEvent reqEvent = CloudEventBuilder.v1()
+        .withId("hello")
+        .withType("example.vertx")
+        .withSource(URI.create("http://localhost"))
+        .build();
+
+    VertxMessageFactory
+        .createWriter(client.postAbs("http://localhost:8080"))
+        .writeBinary(reqEvent)
+        .onSuccess(response -> {
+          CloudEvent responseEvent = VertxMessageFactory
+              .createReader(response)
+              .toEvent();
+        })
+        .onFailure(Throwable::printStackTrace);
+  }
+}
+```
+
+## Examples:
+
+- [Vert.x Client and Server](https://github.com/cloudevents/sdk-java/tree/main/examples/vertx)

docs/index.md

@@ -5,100 +5,133 @@ nav_order: 1
 
 # Java SDK for CloudEvents
 
-A Java API for the [CloudEvents specification](https://github.com/cloudevents/spec)
-
-1. [Supported Specification Features](#supported-specification-features)
-1. [Modules](#modules)
+1. [Introduction](#introduction)
+1. [Supported features](#supported-features)
 1. [Get Started](#get-started)
-1. [Use an event format](#use-an-event-format)
-1. [Use a protocol binding](#use-a-protocol-binding)
+1. [Modules](#modules)
 
-## Supported Specification Features
+## Introduction
 
-Supported features of the specification:
+The Java SDK for CloudEvents is a collection of Java libraries to adopt
+CloudEvents in your Java application.
 
-|                               |  [v0.3](https://github.com/cloudevents/spec/tree/v0.3) | [v1.0](https://github.com/cloudevents/spec/tree/v1.0) |
-| -------- | -- | -- |
-| CloudEvents Core              | :heavy_check_mark: | :heavy_check_mark: |
-| AMQP Protocol Binding         | :x: | :x:  |
-| AVRO Event Format             | :x: | :x: |
-| HTTP Protocol Binding         | :heavy_check_mark: | :heavy_check_mark: |
-| - [Vert.x](https://github.com/cloudevents/sdk-java/tree/master/http/vertx)        | :heavy_check_mark: | :heavy_check_mark: |
-| - [Jakarta Restful WS](https://github.com/cloudevents/sdk-java/tree/master/http/restful-ws) | :heavy_check_mark: | :heavy_check_mark: |
-| JSON Event Format             | :heavy_check_mark: | :heavy_check_mark: |
-| - [Jackson](https://github.com/cloudevents/sdk-java/tree/master/formats/json-jackson) | :heavy_check_mark: | :heavy_check_mark: |
-| [Kafka Protocol Binding](https://github.com/cloudevents/sdk-java/tree/master/kafka)        | :heavy_check_mark: | :heavy_check_mark: |
-| MQTT Protocol Binding         | :x: | :x: |
-| NATS Protocol Binding         | :x: | :x: |
-| Web hook                      | :x: | :x: |
+Using the Java SDK you can:
 
-## Modules
+-   Access, create and manipulate `CloudEvent` inside your application.
+-   Serialize and deserialize `CloudEvent` back and forth using the _CloudEvents
+    Event Format_, like Json.
+-   Read and write `CloudEvent` back and forth to HTTP, Kafka, AMQP using the
+    _CloudEvents Protocol Binding_ implementations we provide for a wide range
+    of well known Java frameworks/libraries.
 
-The CloudEvents SDK for Java is composed by several modules, each one providing a different feature from the different sub specs of [CloudEvents specification](#supported-specification-features):
+## Supported features
 
-* [`cloudevents-api`] Module providing the `CloudEvent` and other base interfaces
-* [`cloudevents-core`] Module providing `CloudEvent` implementation, `CloudEventBuilder` to create `CloudEvent`s programmatically, `EventFormat` to implement [Event Formats](https://github.com/cloudevents/spec/blob/v1.0/spec.md#event-format), `Message`/`MessageVisitor` to implement [Protocol bindings](https://github.com/cloudevents/spec/blob/v1.0/spec.md#protocol-binding)
-* [`cloudevents-json-jackson`] Implementation of [JSON Event format] with [Jackson](https://github.com/FasterXML/jackson)
-* [`cloudevents-http-vertx`] Implementation of [HTTP Protocol Binding] with [Vert.x Core](https://vertx.io/)
-* [`cloudevents-http-restful-ws`] Implementation of [HTTP Protocol Binding] for [Jakarta Restful WS](https://jakarta.ee/specifications/restful-ws/)
-* [`cloudevents-kafka`] Implementation of [Kafka Protocol Binding]
+|                                                    | [v0.3](https://github.com/cloudevents/spec/tree/v0.3) | [v1.0](https://github.com/cloudevents/spec/tree/v1.0) |
+| :------------------------------------------------: | :---------------------------------------------------: | :---------------------------------------------------: |
+|                  CloudEvents Core                  |                  :heavy_check_mark:                   |                  :heavy_check_mark:                   |
+|               AMQP Protocol Binding                |                          :x:                          |                          :x:                          |
+|             - [Proton](amqp-proton.md)             |                  :heavy_check_mark:                   |                  :heavy_check_mark:                   |
+|                 AVRO Event Format                  |                          :x:                          |                          :x:                          |
+|               HTTP Protocol Binding                |                  :heavy_check_mark:                   |                  :heavy_check_mark:                   |
+|             - [Vert.x](http-vertx.md)              |                  :heavy_check_mark:                   |                  :heavy_check_mark:                   |
+| - [Jakarta Restful WS](http-jakarta-restful-ws.md) |                  :heavy_check_mark:                   |                  :heavy_check_mark:                   |
+|              - [Basic](http-basic.md)              |                  :heavy_check_mark:                   |                  :heavy_check_mark:                   |
+|               - [Spring](spring.md)                |                  :heavy_check_mark:                   |                  :heavy_check_mark:                   |
+|               - [http4k][http4k]<sup>†</sup>       |                  :heavy_check_mark:                   |                  :heavy_check_mark:                   |
+|                 JSON Event Format                  |                  :heavy_check_mark:                   |                  :heavy_check_mark:                   |
+|            - [Jackson](json-jackson.md)            |                  :heavy_check_mark:                   |                  :heavy_check_mark:                   |
+|                Protobuf Event Format               |                  :heavy_check_mark:                   |                  :heavy_check_mark:                   |
+|            - [Proto](protobuf.md)                  |                  :heavy_check_mark:                   |                  :heavy_check_mark:                   |
+|                XML Event Format                    |                  :heavy_check_mark:                   |                  :heavy_check_mark:                   |
+|            - [XML](xml.md)                         |                  :heavy_check_mark:                   |                  :heavy_check_mark:                   |
+|         [Kafka Protocol Binding](kafka.md)         |                  :heavy_check_mark:                   |                  :heavy_check_mark:                   |
+|               MQTT Protocol Binding                |                          :x:                          |                          :x:                          |
+|               NATS Protocol Binding                |                          :x:                          |                          :x:                          |
+|                      Web hook                      |                          :x:                          |                          :x:                          |
 
-You can look at the latest published artifacts on [Maven Central](https://search.maven.org/search?q=g:io.cloudevents).
+<sub>† Source/artifacts hosted externally</sub>
 
 ## Get Started
 
-You can start creating events using the `CloudEventBuilder`:
+In order to start learning how to create, access and manipulate `CloudEvent`s,
+check out the [Core module documentation](core.md).
 
-```java
-import io.cloudevents.CloudEvent;
-import io.cloudevents.core.builder.CloudEventBuilder;
-import java.net.URI;
+If you want to serialize and deserialize events and data back and forth to JSON,
+check out the [Jackson Json module documentation](json-jackson.md).
 
-final CloudEvent event = CloudEventBuilder.v1()
-    .withId("000")
-    .withType("example.demo")
-    .withSource(URI.create("http://example.com"))
-    .withData("application/json", "{}".getBytes())
-    .build();
-```
+Depending on the protocol and framework you're using, if you want to send and
+receive CloudEvents, check out the dedicated pages:
 
-Look at [`cloudevents-core`] README for more information.
+-   [AMQP using Proton](amqp-proton.md)
+-   [HTTP using Vert.x](http-vertx.md)
+-   [HTTP using Jakarta EE 8 - Jakarta Restful WS](http-jakarta-restful-ws.md)
+-   [HTTP using Jakarta EE 9+ - Jakarta Restful WS](http-jakarta-restful-ws-jakarta.md)
+-   [HTTP using Spring](spring.md)
+-   [HTTP using Jackson](json-jackson.md)
+-   [Kafka](kafka.md)
 
-## Use an event format
+If you're interested in implementing an object conforming to the `CloudEvent`
+and related interfaces, in order to interoperate with the other components of
+the SDK, check out the [API module documentation](api.md).
 
-Event formats implementations are auto-discovered through an SPI. You can use them accessing through `EventFormatProvider`.
-For example, given you have in your classpath the [`cloudevents-json-jackson`] module, you can serialize/deserialize an event to/from JSON using:
+You can also check out the
+[**Examples**](https://github.com/cloudevents/sdk-java/tree/main/examples).
 
-```java
-import io.cloudevents.core.format.EventFormatProvider;
-import io.cloudevents.jackson.JsonFormat;
+## Modules
 
-EventFormat format = EventFormatProvider
-  .getInstance()
-  .resolveFormat(JsonFormat.CONTENT_TYPE);
+The CloudEvents SDK for Java is composed by several modules, each one providing
+a different feature from the different sub specs of
+[CloudEvents specification](#supported-features):
 
-// Serialize event
-byte[] serialized = format.serialize(event);
+-   [`cloudevents-api`] Module providing the `CloudEvent` and other base
+    interfaces
+-   [`cloudevents-core`] Module providing `CloudEvent` implementation,
+    `CloudEventBuilder` to create `CloudEvent`s programmatically, `EventFormat`
+    to implement
+    [Event Formats](https://github.com/cloudevents/spec/blob/v1.0/spec.md#event-format),
+    `MessageReader` /`MessageWriter` to implement
+    [Protocol bindings](https://github.com/cloudevents/spec/blob/v1.0/spec.md#protocol-binding)
+-   [`cloudevents-bom`] Module providing a
+    [bill of materials (BOM)](https://maven.apache.org/guides/introduction/introduction-to-dependency-mechanism.html#bill-of-materials-bom-poms)
+    for easier integration of CloudEvents in other projects
+-   [`cloudevents-json-jackson`] Implementation of [JSON Event format] with
+    [Jackson](https://github.com/FasterXML/jackson)
+-   [`cloudevents-protobuf`] Implementation of [Protobuf Event format] using code generated
+    from the standard [protoc](https://github.com/protocolbuffers/protobuf) compiler.
+-   [`cloudevents-xml`] Implementation of the XML Event Format.
+-   [`cloudevents-http-vertx`] Implementation of [HTTP Protocol Binding] with
+    [Vert.x Core](https://vertx.io/)
+-   [`cloudevents-http-restful-ws`] Implementation of [HTTP Protocol Binding]
+    for [Jakarta EE 8 Restful WS](https://jakarta.ee/specifications/restful-ws/2.1/)
+-   [`cloudevents-http-restful-ws-jakarta`] Implementation of  [HTTP Protocol Binding]
+      for [Jakarta EE 9+ Restful WS](https://jakarta.ee/specifications/restful-ws/)
+-   [`cloudevents-http-basic`] Generic implementation of [HTTP Protocol
+    Binding], primarily intended for integrators
+-   [`cloudevents-kafka`] Implementation of [Kafka Protocol Binding]
+-   [`cloudevents-amqp-proton`] Implementation of [AMQP Protocol Binding] with
+    [Proton](http://qpid.apache.org/proton/)
+-   [`cloudevents-spring`] Integration of `CloudEvent` with different Spring
+    APIs, like MVC, WebFlux and Messaging
 
-// Deserialize event
-CloudEvent event = format.deserialize(bytes);
-```
+You can look at the latest published artifacts on
+[Maven Central](https://search.maven.org/search?q=g:io.cloudevents).
 
-## Use a protocol binding
-
-Each protocol binding has its own APIs, depending on the library/framework it's integrating with.
-Check out the documentation of the protocol binding modules:
-
-* [`cloudevents-http-vertx`]
-* [`cloudevents-http-restful-ws`]
-* [`cloudevents-kafka`]
-
-[JSON Event Format]: https://github.com/cloudevents/spec/blob/v1.0/json-format.md
+[JSON Event format]: https://github.com/cloudevents/spec/blob/v1.0/json-format.md
+[Protobuf Event format]: https://github.com/cloudevents/spec/blob/v1.0.1/protobuf-format.md
 [HTTP Protocol Binding]: https://github.com/cloudevents/spec/blob/v1.0/http-protocol-binding.md
 [Kafka Protocol Binding]: https://github.com/cloudevents/spec/blob/v1.0/kafka-protocol-binding.md
-[`cloudevents-api`]: https://github.com/cloudevents/sdk-java/tree/master/api
-[`cloudevents-core`]: https://github.com/cloudevents/sdk-java/tree/master/core
-[`cloudevents-json-jackson`]: https://github.com/cloudevents/sdk-java/tree/master/formats/json-jackson
-[`cloudevents-http-vertx`]: https://github.com/cloudevents/sdk-java/tree/master/http/vertx
-[`cloudevents-http-restful-ws`]: https://github.com/cloudevents/sdk-java/tree/master/http/restful-ws
-[`cloudevents-kafka`]: https://github.com/cloudevents/sdk-java/tree/master/kafka
+[AMQP Protocol Binding]: https://github.com/cloudevents/spec/blob/v1.0/amqp-protocol-binding.md
+[`cloudevents-api`]: https://github.com/cloudevents/sdk-java/tree/main/api
+[`cloudevents-bom`]: https://github.com/cloudevents/sdk-java/tree/main/bom
+[`cloudevents-core`]: https://github.com/cloudevents/sdk-java/tree/main/core
+[`cloudevents-json-jackson`]: https://github.com/cloudevents/sdk-java/tree/main/formats/json-jackson
+[`cloudevents-protobuf`]: https://github.com/cloudevents/sdk-java/tree/main/formats/protobuf
+[`cloudevents-xml`]: https://github.com/cloudevents/sdk-java/tree/main/formats/xml
+[`cloudevents-http-vertx`]: https://github.com/cloudevents/sdk-java/tree/main/http/vertx
+[`cloudevents-http-basic`]: https://github.com/cloudevents/sdk-java/tree/main/http/basic
+[`cloudevents-http-restful-ws`]: https://github.com/cloudevents/sdk-java/tree/main/http/restful-ws
+[`cloudevents-http-restful-ws-jakarta`]: https://github.com/cloudevents/sdk-java/tree/main/http/restful-ws-jakarta
+[`cloudevents-kafka`]: https://github.com/cloudevents/sdk-java/tree/main/kafka
+[`cloudevents-amqp-proton`]: https://github.com/cloudevents/sdk-java/tree/main/amqp
+[`cloudevents-spring`]: https://github.com/cloudevents/sdk-java/tree/main/spring
+[http4k]: https://www.http4k.org/guide/modules/cloud_events/

docs/json-jackson.md

@@ -0,0 +1,67 @@
+---
+title: CloudEvents Json Jackson
+nav_order: 4
+---
+
+# CloudEvents Json Jackson
+
+[![Javadocs](http://www.javadoc.io/badge/io.cloudevents/cloudevents-json-jackson.svg?color=green)](http://www.javadoc.io/doc/io.cloudevents/cloudevents-json-jackson)
+
+This module provides the JSON `EventFormat` implementation using Jackson and a
+`PojoCloudEventDataMapper` to convert `CloudEventData` to POJOs using the
+Jackson `ObjectMapper`.
+
+For Maven based projects, use the following dependency:
+
+```xml
+<dependency>
+    <groupId>io.cloudevents</groupId>
+    <artifactId>cloudevents-json-jackson</artifactId>
+    <version>4.0.1</version>
+</dependency>
+```
+
+## Using the JSON Event Format
+
+You don't need to perform any operation to configure the module, more than
+adding the dependency to your project:
+
+```java
+import io.cloudevents.CloudEvent;
+import io.cloudevents.core.format.ContentType;
+import io.cloudevents.core.provider.EventFormatProvider;
+import io.cloudevents.core.builder.CloudEventBuilder;
+
+CloudEvent event = CloudEventBuilder.v1()
+    .withId("hello")
+    .withType("example.vertx")
+    .withSource(URI.create("http://localhost"))
+    .build();
+
+byte[]serialized = EventFormatProvider
+    .getInstance()
+    .resolveFormat(ContentType.JSON)
+    .serialize(event);
+```
+
+The `EventFormatProvider` will resolve automatically the `JsonFormat` using the
+`ServiceLoader` APIs.
+
+## Mapping `CloudEventData` to POJOs using Jackson `ObjectMapper`
+
+Using the Jackson `ObjectMapper`, you can easily extract a POJO starting from
+any `CloudEventData`:
+
+```java
+import io.cloudevents.core.data.PojoCloudEventData;
+import io.cloudevents.jackson.PojoCloudEventDataMapper;
+
+import static io.cloudevents.core.CloudEventUtils.mapData;
+
+PojoCloudEventData<User> cloudEventData = mapData(
+    inputEvent,
+    PojoCloudEventDataMapper.from(objectMapper,User.class)
+);
+// check if cloudEventData is null
+User user = cloudEventData.getValue();
+```

docs/kafka.md

@@ -0,0 +1,122 @@
+---
+title: CloudEvents Kafka
+nav_order: 5
+---
+
+# CloudEvents Kafka
+
+[![Javadocs](http://www.javadoc.io/badge/io.cloudevents/cloudevents-kafka.svg?color=green)](http://www.javadoc.io/doc/io.cloudevents/cloudevents-kafka)
+
+Implementation of Kafka Protocol Binding to send and receive CloudEvents.
+
+For Maven based projects, use the following to configure the
+[Kafka Protocol Binding](https://github.com/cloudevents/spec/blob/main/kafka-protocol-binding.md):
+
+```xml
+
+<dependency>
+    <groupId>io.cloudevents</groupId>
+    <artifactId>cloudevents-kafka</artifactId>
+    <version>4.0.1</version>
+</dependency>
+```
+
+### Producing CloudEvents
+
+To produce CloudEvents in Kafka, configure the KafkaProducer to use the provided
+`CloudEventSerializer`:
+
+```java
+import java.util.Properties;
+
+import io.cloudevents.CloudEvent;
+import io.cloudevents.core.builder.CloudEventBuilder;
+import io.cloudevents.kafka.CloudEventSerializer;
+import org.apache.kafka.clients.producer.KafkaProducer;
+import org.apache.kafka.clients.producer.ProducerConfig;
+import org.apache.kafka.common.serialization.StringSerializer;
+
+public class CloudEventProducer {
+
+    public static void main(String[] args) {
+        Properties props = new Properties();
+
+        // Other config props
+        props.put(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, StringSerializer.class);
+        props.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, CloudEventSerializer.class);
+
+        try (KafkaProducer<String, CloudEvent> producer = new KafkaProducer<>(props)) {
+
+            // Build an event
+            CloudEvent event = CloudEventBuilder.v1()
+                .withId("hello")
+                .withType("example.kafka")
+                .withSource(URI.create("http://localhost"))
+                .build();
+
+            // Produce the event
+            producer.send(new ProducerRecord<>("your.topic", event));
+        }
+    }
+}
+```
+
+You can configure the Encoding and EventFormat to use to emit the event.
+
+Check out the
+[`CloudEventSerializer`](https://github.com/cloudevents/sdk-java/tree/main/kafka/src/main/java/io/cloudevents/kafka/CloudEventSerializer.java)
+javadoc for more info.
+
+### Partition key extension
+
+If you want your producer to use the `partitionkey` extension, you can use the
+PartitionKeyExtensionInterceptor.
+
+```java
+producerProps.put(
+    ProducerConfig.INTERCEPTOR_CLASSES_CONFIG,
+    io.cloudevents.kafka.PartitionKeyExtensionInterceptor.class
+);
+```
+
+When using in your producer, this interceptor will pick the `partitionkey`
+extension from the event and will set it as record key, regardless of the input record key.
+Check out the [`PartitionKeyExtensionInterceptor`](https://github.com/cloudevents/sdk-java/tree/main/kafka/src/main/java/io/cloudevents/kafka/PartitionKeyExtensionInterceptor.java)
+javadoc for more info.
+
+## Consuming CloudEvents
+
+To consume CloudEvents in Kafka, configure the KafkaConsumer to use the provided
+`CloudEventDeserializer`:
+
+```java
+import java.time.Duration;
+import java.util.Properties;
+
+import io.cloudevents.CloudEvent;
+import io.cloudevents.kafka.CloudEventDeserializer;
+import org.apache.kafka.clients.consumer.ConsumerConfig;
+import org.apache.kafka.clients.consumer.ConsumerRecords;
+import org.apache.kafka.clients.consumer.KafkaConsumer;
+import org.apache.kafka.common.serialization.StringDeserializer;
+
+public class CloudEventConsumer {
+
+    public static void main(String[] args) {
+        Properties props = new Properties();
+
+        // Other config props
+        props.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class);
+        props.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, CloudEventDeserializer.class);
+
+        try (KafkaConsumer<String, CloudEvent> consumer = new KafkaConsumer<>(props)) {
+
+            ConsumerRecords<String, CloudEvent> records = consumer.poll(Duration.ofSeconds(10));
+
+            records.forEach(rec -> {
+                System.out.println(rec.value().toString());
+            });
+        }
+    }
+}
+```

docs/protobuf.md

@@ -0,0 +1,96 @@
+---
+title: CloudEvents Protocol Buffers
+nav_order: 4
+---
+
+# CloudEvents Protocol Buffers
+
+[![Javadocs](http://www.javadoc.io/badge/io.cloudevents/cloudevents-protobuf.svg?color=green)](http://www.javadoc.io/doc/io.cloudevents/cloudevents-protobuf)
+
+This module provides the Protocol Buffer (protobuf) `EventFormat` implementation using the Java
+Protobuf runtime and classes generated from the CloudEvents
+[proto spec](https://github.com/cloudevents/spec/blob/v1.0.1/spec.proto).
+
+# Setup
+For Maven based projects, use the following dependency:
+
+```xml
+<dependency>
+    <groupId>io.cloudevents</groupId>
+    <artifactId>cloudevents-protobuf</artifactId>
+    <version>4.0.1</version>
+</dependency>
+```
+
+No further configuration is required is use the module.
+
+## Using the Protobuf Event Format
+
+### Event serialization
+
+```java
+import io.cloudevents.CloudEvent;
+import io.cloudevents.core.format.ContentType;
+import io.cloudevents.core.provider.EventFormatProvider;
+import io.cloudevents.core.builder.CloudEventBuilder;
+
+CloudEvent event = CloudEventBuilder.v1()
+    .withId("hello")
+    .withType("example.vertx")
+    .withSource(URI.create("http://localhost"))
+    .build();
+
+byte[]serialized = EventFormatProvider
+    .getInstance()
+    .resolveFormat(ContentType.PROTO)
+    .serialize(event);
+```
+
+The `EventFormatProvider` will automatically resolve the `ProtobufFormat` using the
+`ServiceLoader` APIs.
+
+## Passing Protobuf messages as CloudEvent data.
+
+The `ProtoCloudEventData` capability provides a convenience mechanism to handle Protobuf message object data.
+
+### Building
+
+```java
+// Build my business event message.
+com.google.protobuf.Message myMessage = ..... ;
+
+// Wrap the protobuf message as CloudEventData.
+CloudEventData ceData = ProtoCloudEventData.wrap(myMessage);
+
+// Build the CloudEvent
+CloudEvent event = CloudEventBuilder.v1()
+    .withId("hello")
+    .withType("example.protodata")
+    .withSource(URI.create("http://localhost"))
+    .withData(ceData)
+    .build();
+```
+
+### Reading
+
+If the `ProtobufFormat` is used to deserialize a CloudEvent that contains a protobuf message object as data you can use
+the `ProtoCloudEventData` to access it as an 'Any' directly.
+
+```java
+
+// Deserialize the event.
+CloudEvent myEvent = eventFormat.deserialize(raw);
+
+// Get the Data
+CloudEventData eventData = myEvent.getData();
+
+if (ceData instanceOf ProtoCloudEventData) {
+
+    // Obtain the protobuf 'any'
+    Any anAny = ((ProtoCloudEventData) eventData).getAny();
+
+    ...
+}
+
+```
+