diff --git a/api/src/main/java/io/cloudevents/Attributes.java b/api/src/main/java/io/cloudevents/Attributes.java
index 5ecbc5a3..25782574 100644
--- a/api/src/main/java/io/cloudevents/Attributes.java
+++ b/api/src/main/java/io/cloudevents/Attributes.java
@@ -60,4 +60,8 @@ public interface Attributes {
 
 	Optional<ZonedDateTime> getTime();
 
+    Attributes toV03();
+
+    Attributes toV1();
+
 }
diff --git a/api/src/main/java/io/cloudevents/CloudEvent.java b/api/src/main/java/io/cloudevents/CloudEvent.java
index 025ed2d4..132c5a48 100644
--- a/api/src/main/java/io/cloudevents/CloudEvent.java
+++ b/api/src/main/java/io/cloudevents/CloudEvent.java
@@ -54,23 +54,23 @@ public interface CloudEvent {
      */
     Map<String, Object> getExtensions();
 
-    /**
-     * Write an extension into this cloud event
-     * @param e
-     */
-    default void writeExtension(Extension e) {
-        e.writeToEvent(this);
-    }
+    CloudEvent toV03();
 
-    static io.cloudevents.v1.CloudEventBuilder build() {
-        return buildV1();
-    }
+    CloudEvent toV1();
 
     static io.cloudevents.v1.CloudEventBuilder buildV1() {
         return new io.cloudevents.v1.CloudEventBuilder();
     }
 
+    static io.cloudevents.v1.CloudEventBuilder buildV1(CloudEvent event) {
+        return new io.cloudevents.v1.CloudEventBuilder(event);
+    }
+
     static io.cloudevents.v03.CloudEventBuilder buildV03() {
         return new io.cloudevents.v03.CloudEventBuilder();
     }
+
+    static io.cloudevents.v03.CloudEventBuilder buildV03(CloudEvent event) {
+        return new io.cloudevents.v03.CloudEventBuilder(event);
+    }
 }
diff --git a/api/src/main/java/io/cloudevents/Extension.java b/api/src/main/java/io/cloudevents/Extension.java
index f99fd0d7..5f1f8d85 100644
--- a/api/src/main/java/io/cloudevents/Extension.java
+++ b/api/src/main/java/io/cloudevents/Extension.java
@@ -1,9 +1,11 @@
 package io.cloudevents;
 
+import java.util.Map;
+
 public interface Extension {
 
     void readFromEvent(CloudEvent event);
 
-    void writeToEvent(CloudEvent event);
+    Map<String, Object> asMap();
 
 }
diff --git a/api/src/main/java/io/cloudevents/extensions/DistributedTracingExtension.java b/api/src/main/java/io/cloudevents/extensions/DistributedTracingExtension.java
index 4b09e54e..5915696b 100644
--- a/api/src/main/java/io/cloudevents/extensions/DistributedTracingExtension.java
+++ b/api/src/main/java/io/cloudevents/extensions/DistributedTracingExtension.java
@@ -3,6 +3,10 @@ package io.cloudevents.extensions;
 import io.cloudevents.CloudEvent;
 import io.cloudevents.Extension;
 
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.Map;
+
 public final class DistributedTracingExtension implements Extension {
 
     public static final String TRACEPARENT = "traceparent";
@@ -42,13 +46,11 @@ public final class DistributedTracingExtension implements Extension {
     }
 
     @Override
-    public void writeToEvent(CloudEvent event) {
-        if (traceparent != null) {
-            event.getExtensions().put(TRACEPARENT, this.traceparent);
-        }
-        if (tracestate != null) {
-            event.getExtensions().put(TRACESTATE, this.tracestate);
-        }
+    public Map<String, Object> asMap() {
+        HashMap<String, Object> map = new HashMap<>();
+        map.put(TRACEPARENT, this.traceparent);
+        map.put(TRACESTATE, this.tracestate);
+        return Collections.unmodifiableMap(map);
     }
 
     @Override
diff --git a/api/src/main/java/io/cloudevents/extensions/ExtensionsParser.java b/api/src/main/java/io/cloudevents/extensions/ExtensionsParser.java
index a0d2fa7d..218151cf 100644
--- a/api/src/main/java/io/cloudevents/extensions/ExtensionsParser.java
+++ b/api/src/main/java/io/cloudevents/extensions/ExtensionsParser.java
@@ -18,6 +18,8 @@ public final class ExtensionsParser {
 
     private HashMap<Class<?>, Supplier<Extension>> extensionFactories;
 
+
+    // TODO SPI in future?
     private ExtensionsParser() {
         this.extensionFactories = new HashMap<>();
         registerExtension(DistributedTracingExtension.class, DistributedTracingExtension::new);
diff --git a/api/src/main/java/io/cloudevents/impl/BaseCloudEventBuilder.java b/api/src/main/java/io/cloudevents/impl/BaseCloudEventBuilder.java
index 105c59a0..9c1052d1 100644
--- a/api/src/main/java/io/cloudevents/impl/BaseCloudEventBuilder.java
+++ b/api/src/main/java/io/cloudevents/impl/BaseCloudEventBuilder.java
@@ -6,9 +6,7 @@ import io.cloudevents.CloudEvent;
 import io.cloudevents.Extension;
 
 import java.net.URI;
-import java.util.ArrayList;
 import java.util.HashMap;
-import java.util.List;
 import java.util.Map;
 
 public abstract class BaseCloudEventBuilder<B extends BaseCloudEventBuilder<B, T>, T extends Attributes> {
@@ -18,15 +16,25 @@ public abstract class BaseCloudEventBuilder<B extends BaseCloudEventBuilder<B, T
 
     private Object data;
     private Map<String, Object> extensions;
-    private List<Extension> materializedExtensions;
 
     @SuppressWarnings("unchecked")
     public BaseCloudEventBuilder() {
         this.self = (B)this;
         this.extensions = new HashMap<>();
-        this.materializedExtensions = new ArrayList<>();
     }
 
+    @SuppressWarnings("unchecked")
+    public BaseCloudEventBuilder(CloudEvent event) {
+        this.self = (B)this;
+
+        CloudEventImpl ev = (CloudEventImpl) event;
+        this.setAttributes(ev.getAttributes());
+        this.data = ev.getRawData();
+        this.extensions = new HashMap<>(ev.getExtensions());
+    }
+
+    protected abstract void setAttributes(Attributes attributes);
+
     protected abstract B withDataContentType(String contentType);
 
     protected abstract B withDataSchema(URI dataSchema);
@@ -49,15 +57,15 @@ public abstract class BaseCloudEventBuilder<B extends BaseCloudEventBuilder<B, T
     }
 
     public B withData(String contentType, URI dataSchema, String data) {
-        return withEncodedata(contentType, dataSchema, (Object) data);
+        return withEncodeData(contentType, dataSchema, (Object) data);
     }
 
     public B withData(String contentType, URI dataSchema, byte[] data) {
-        return withEncodedata(contentType, dataSchema, (Object) data);
+        return withEncodeData(contentType, dataSchema, (Object) data);
     }
 
     public B withData(String contentType, URI dataSchema, JsonNode data) {
-        return withEncodedata(contentType, dataSchema, (Object) data);
+        return withEncodeData(contentType, dataSchema, (Object) data);
     }
 
     public B withExtension(String key, String value) {
@@ -76,19 +84,12 @@ public abstract class BaseCloudEventBuilder<B extends BaseCloudEventBuilder<B, T
     }
 
     public B withExtension(Extension extension) {
-        this.materializedExtensions.add(extension);
+        this.extensions.putAll(extension.asMap());
         return self;
     }
 
     public CloudEvent build() {
-        CloudEvent event = new CloudEventImpl(this.buildAttributes(), data, extensions);
-
-        // Write materialized extensions into the event
-        for (Extension ext : this.materializedExtensions) {
-            ext.writeToEvent(event);
-        }
-
-        return event;
+        return new CloudEventImpl(this.buildAttributes(), data, extensions);
     }
 
     private B withEncodedData(String contentType, Object data) {
@@ -97,7 +98,7 @@ public abstract class BaseCloudEventBuilder<B extends BaseCloudEventBuilder<B, T
         return self;
     }
 
-    private B withEncodedata(String contentType, URI dataSchema, Object data) {
+    private B withEncodeData(String contentType, URI dataSchema, Object data) {
         withDataContentType(contentType);
         withDataSchema(dataSchema);
         this.data = data;
diff --git a/api/src/main/java/io/cloudevents/impl/CloudEventImpl.java b/api/src/main/java/io/cloudevents/impl/CloudEventImpl.java
index c443591d..25fb0f67 100644
--- a/api/src/main/java/io/cloudevents/impl/CloudEventImpl.java
+++ b/api/src/main/java/io/cloudevents/impl/CloudEventImpl.java
@@ -13,14 +13,11 @@ import io.cloudevents.json.Json;
 
 import java.io.IOException;
 import java.nio.charset.StandardCharsets;
-import java.util.HashMap;
-import java.util.Map;
-import java.util.Objects;
-import java.util.Optional;
+import java.util.*;
 
 @JsonSerialize(using = CloudEventSerializer.class)
 @JsonDeserialize(using = CloudEventDeserializer.class)
-public class CloudEventImpl implements CloudEvent {
+public final class CloudEventImpl implements CloudEvent {
 
     private final Attributes attributes;
     private final Object data;
@@ -109,6 +106,28 @@ public class CloudEventImpl implements CloudEvent {
 
     @Override
     public Map<String, Object> getExtensions() {
-        return extensions;
+        return Collections.unmodifiableMap(extensions);
+    }
+
+    @Override
+    public CloudEvent toV03() {
+        return new CloudEventImpl(
+            attributes.toV03(),
+            data,
+            extensions
+        );
+    }
+
+    @Override
+    public CloudEvent toV1() {
+        return new CloudEventImpl(
+            attributes.toV1(),
+            data,
+            extensions
+        );
+    }
+
+    protected Object getRawData() {
+        return data;
     }
 }
diff --git a/api/src/main/java/io/cloudevents/v03/AttributesImpl.java b/api/src/main/java/io/cloudevents/v03/AttributesImpl.java
index 7697a8f6..d527585a 100644
--- a/api/src/main/java/io/cloudevents/v03/AttributesImpl.java
+++ b/api/src/main/java/io/cloudevents/v03/AttributesImpl.java
@@ -32,21 +32,16 @@ import java.util.Optional;
 public class AttributesImpl implements Attributes {
 
 	private final String id;
-
 	private final URI source;
-
 	private final String type;
-
 	private final ZonedDateTime time;
 	private final URI schemaurl;
-
 	private final String datacontenttype;
-
 	private final String subject;
 
-	AttributesImpl(String id, URI source, String type,
-			ZonedDateTime time, URI schemaurl,
-			String datacontenttype, String subject) {
+	public AttributesImpl(String id, URI source, String type,
+                          ZonedDateTime time, URI schemaurl,
+                          String datacontenttype, String subject) {
 		this.id = id;
 		this.source = source;
 		this.type = type;
@@ -72,6 +67,25 @@ public class AttributesImpl implements Attributes {
 	public Optional<ZonedDateTime> getTime() {
 		return Optional.ofNullable(time);
 	}
+
+    @Override
+    public Attributes toV03() {
+        return this;
+    }
+
+    @Override
+    public Attributes toV1() {
+        return new io.cloudevents.v1.AttributesImpl(
+            this.id,
+            this.source,
+            this.type,
+            this.datacontenttype,
+            this.schemaurl,
+            this.subject,
+            this.time
+        );
+    }
+
     public Optional<URI> getDataSchema() {
         return getSchemaUrl();
     }
diff --git a/api/src/main/java/io/cloudevents/v03/CloudEventBuilder.java b/api/src/main/java/io/cloudevents/v03/CloudEventBuilder.java
index f0ce06d2..7a8b443d 100644
--- a/api/src/main/java/io/cloudevents/v03/CloudEventBuilder.java
+++ b/api/src/main/java/io/cloudevents/v03/CloudEventBuilder.java
@@ -15,6 +15,8 @@
  */
 package io.cloudevents.v03;
 
+import io.cloudevents.Attributes;
+import io.cloudevents.CloudEvent;
 import io.cloudevents.impl.BaseCloudEventBuilder;
 
 import java.net.URI;
@@ -29,20 +31,35 @@ import java.time.ZonedDateTime;
  */
 public final class CloudEventBuilder extends BaseCloudEventBuilder<CloudEventBuilder, AttributesImpl>  {
 
-	public CloudEventBuilder() {
-		super();
-	}
-
 	private String id;
 	private URI source;
-
 	private String type;
-
 	private ZonedDateTime time;
 	private URI schemaurl;
 	private String datacontenttype;
 	private String subject;
 
+    public CloudEventBuilder() {
+        super();
+    }
+
+    public CloudEventBuilder(CloudEvent event) {
+        super(event);
+    }
+
+    @Override
+    protected void setAttributes(Attributes attributes) {
+        AttributesImpl attr = (AttributesImpl) attributes.toV03();
+        this
+            .withId(attr.getId())
+            .withSource(attr.getSource())
+            .withType(attr.getType());
+        attr.getDataContentType().ifPresent(this::withDataContentType);
+        attr.getSchemaUrl().ifPresent(this::withSchemaUrl);
+        attr.getSubject().ifPresent(this::withSubject);
+        attr.getTime().ifPresent(this::withTime);
+    }
+
 	public CloudEventBuilder withId(String id) {
 		this.id = id;
 		return this;
diff --git a/api/src/main/java/io/cloudevents/v03/http/AttributeMapper.java b/api/src/main/java/io/cloudevents/v03/http/AttributeMapper.java
deleted file mode 100644
index 9e00b206..00000000
--- a/api/src/main/java/io/cloudevents/v03/http/AttributeMapper.java
+++ /dev/null
@@ -1,80 +0,0 @@
-/**
- * Copyright 2019 The CloudEvents Authors
- *
- * 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
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * 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.v03.http;
-
-import static java.util.stream.Collectors.toMap;
-
-import java.util.Locale;
-import java.util.Map;
-import java.util.Objects;
-import java.util.Optional;
-import java.util.AbstractMap.SimpleEntry;
-import java.util.Map.Entry;
-import java.util.concurrent.atomic.AtomicReference;
-
-import io.cloudevents.fun.BinaryFormatAttributeMapper;
-import io.cloudevents.v03.ContextAttributes;
-
-/**
- *
- * @author fabiojose
- * @version 0.3
- */
-public class AttributeMapper {
-	private AttributeMapper() {}
-
-	static final String HEADER_PREFIX = "ce-";
-
-	/**
-	 * Following the signature of {@link BinaryFormatAttributeMapper#map(Map)}
-	 * @param headers Map of HTTP request
-	 * @return Map with spec attributes and values without parsing
-	 * @see ContextAttributes
-	 */
-	public static Map<String, String> map(final Map<String, Object> headers) {
-		Objects.requireNonNull(headers);
-
-		final AtomicReference<Optional<Entry<String, Object>>> ct =
-				new AtomicReference<>();
-
-		ct.set(Optional.empty());
-
-		Map<String, String> result = headers.entrySet()
-			.stream()
-			.filter(header -> null!= header.getValue())
-			.map(header -> new SimpleEntry<>(header.getKey()
-					.toLowerCase(Locale.US), header.getValue()))
-			.peek(header -> {
-				if("content-type".equals(header.getKey())) {
-					ct.set(Optional.ofNullable(header));
-				}
-			})
-			.filter(header -> header.getKey().startsWith(HEADER_PREFIX))
-			.map(header -> new SimpleEntry<>(header.getKey()
-					.substring(HEADER_PREFIX.length()), header.getValue()))
-			.map(header -> new SimpleEntry<>(header.getKey(),
-					header.getValue().toString()))
-			.collect(toMap(Entry::getKey, Entry::getValue));
-
-		ct.get().ifPresent(contentType -> {
-			result.put(ContextAttributes.DATACONTENTTYPE.name(),
-					contentType.getValue().toString());
-		});
-
-		return result;
-	}
-
-}
diff --git a/api/src/main/java/io/cloudevents/v03/http/ExtensionMapper.java b/api/src/main/java/io/cloudevents/v03/http/ExtensionMapper.java
deleted file mode 100644
index 4a7a2215..00000000
--- a/api/src/main/java/io/cloudevents/v03/http/ExtensionMapper.java
+++ /dev/null
@@ -1,65 +0,0 @@
-/**
- * Copyright 2019 The CloudEvents Authors
- *
- * 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
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * 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.v03.http;
-
-import java.util.List;
-import java.util.Locale;
-import java.util.Map;
-import java.util.Objects;
-import java.util.AbstractMap.SimpleEntry;
-import java.util.Map.Entry;
-import java.util.stream.Collectors;
-
-import io.cloudevents.fun.FormatExtensionMapper;
-import io.cloudevents.v03.ContextAttributes;
-
-/**
- * 
- * @author fabiojose
- * @version 0.3
- */
-public class ExtensionMapper {
-	private ExtensionMapper() {}
-	
-	private static final List<String> RESERVED_HEADERS = 
-			ContextAttributes.VALUES.stream()
-				.map(attribute -> AttributeMapper
-						.HEADER_PREFIX + attribute)
-				.collect(Collectors.toList());
-		static {
-			RESERVED_HEADERS.add("content-type");
-		};
-
-	/**
-	 * Following the signature of {@link FormatExtensionMapper}
-	 * @param headers The HTTP headers
-	 * @return The potential extensions without parsing
-	 */
-	public static Map<String, String> map(Map<String, Object> headers) {
-		Objects.requireNonNull(headers);
-		
-		// remove all reserved words and the remaining may be extensions
-		return 
-		headers.entrySet()
-			.stream()
-			.filter(header -> null!= header.getValue())
-			.map(header -> new SimpleEntry<>(header.getKey()
-					.toLowerCase(Locale.US), header.getValue().toString()))
-			.filter(header -> !RESERVED_HEADERS.contains(header.getKey()))
-			.collect(Collectors.toMap(Entry::getKey, Entry::getValue));
-	}
-
-}
diff --git a/api/src/main/java/io/cloudevents/v03/http/HeaderMapper.java b/api/src/main/java/io/cloudevents/v03/http/HeaderMapper.java
deleted file mode 100644
index d073dae7..00000000
--- a/api/src/main/java/io/cloudevents/v03/http/HeaderMapper.java
+++ /dev/null
@@ -1,79 +0,0 @@
-/**
- * Copyright 2019 The CloudEvents Authors
- *
- * 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
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * 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.v03.http;
-
-import static io.cloudevents.v03.http.AttributeMapper.HEADER_PREFIX;
-
-import java.util.Locale;
-import java.util.Map;
-import java.util.Objects;
-import java.util.Optional;
-import java.util.AbstractMap.SimpleEntry;
-import java.util.Map.Entry;
-import java.util.stream.Collectors;
-
-import io.cloudevents.fun.FormatHeaderMapper;
-import io.cloudevents.v03.ContextAttributes;
-
-/**
- *
- * @author fabiojose
- *
- */
-public class HeaderMapper {
-	private HeaderMapper() {}
-
-	private static final String HTTP_CONTENT_TYPE = "Content-Type";
-
-	/**
-	 * Following the signature of {@link FormatHeaderMapper}
-	 * @param attributes The map of attributes created by {@link AttributeMapper}
-	 * @param extensions The map of extensions created by {@link ExtensionMapper}
-	 * @return The map of HTTP Headers
-	 */
-	public static Map<String, String> map(Map<String, String> attributes,
-			Map<String, String> extensions) {
-		Objects.requireNonNull(attributes);
-		Objects.requireNonNull(extensions);
-
-		Map<String, String> result = attributes.entrySet()
-			.stream()
-			.filter(attribute -> null!= attribute.getValue())
-			.map(header -> new SimpleEntry<>(header.getKey()
-					.toLowerCase(Locale.US), header.getValue()))
-			.filter(header -> !header.getKey()
-					.equals(ContextAttributes.DATACONTENTTYPE.name()))
-			.map(header -> new SimpleEntry<>(HEADER_PREFIX+header.getKey(),
-					header.getValue()))
-			.collect(Collectors.toMap(Entry::getKey, Entry::getValue));
-
-		result.putAll(
-			extensions.entrySet()
-				.stream()
-				.filter(extension -> null!= extension.getValue())
-				.collect(Collectors.toMap(Entry::getKey, Entry::getValue))
-		);
-
-		Optional.ofNullable(attributes
-				.get(ContextAttributes.DATACONTENTTYPE.name()))
-			.ifPresent((dct) -> {
-				result.put(HTTP_CONTENT_TYPE, dct);
-			});
-
-		return result;
-	}
-
-}
diff --git a/api/src/main/java/io/cloudevents/v03/http/Marshallers.java b/api/src/main/java/io/cloudevents/v03/http/Marshallers.java
deleted file mode 100644
index 1404b12e..00000000
--- a/api/src/main/java/io/cloudevents/v03/http/Marshallers.java
+++ /dev/null
@@ -1,83 +0,0 @@
-/**
- * Copyright 2019 The CloudEvents Authors
- *
- * 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
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * 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.v03.http;
-
-import java.util.HashMap;
-import java.util.Map;
-
-import io.cloudevents.CloudEvent;
-import io.cloudevents.extensions.ExtensionFormat;
-import io.cloudevents.format.BinaryMarshaller;
-import io.cloudevents.format.StructuredMarshaller;
-import io.cloudevents.format.Wire;
-import io.cloudevents.format.builder.EventStep;
-import io.cloudevents.json.Json;
-import io.cloudevents.v03.Accessor;
-import io.cloudevents.v03.AttributesImpl;
-import io.cloudevents.v03.CloudEventImpl;
-
-/**
- * 
- * @author fabiojose
- * @version 0.3
- */
-public class Marshallers {
-	private Marshallers() {}
-
-	private static final Map<String, String> NO_HEADERS = 
-			new HashMap<String, String>();
-		
-	/**
-	 * Builds a Binary Content Mode marshaller to marshal cloud events as JSON for
-	 * HTTP Transport Binding
-	 * 
-	 * @param <T> The 'data' type
-	 * @return A step to provide the {@link CloudEventImpl} and marshal as JSON
-	 * @see BinaryMarshaller
-	 */
-	public static <T> EventStep<AttributesImpl, T, String, String> binary() {
-		return 
-			BinaryMarshaller.<AttributesImpl, T, String, String>
-			  builder()
-				.map(AttributesImpl::marshal)
-				.map(Accessor::extensionsOf)
-				.map(ExtensionFormat::marshal)
-				.map(HeaderMapper::map)
-				.map(Json.<T, String>marshaller()::marshal)
-				.builder(Wire<String, String, String>::new);
-	}
-	
-	/**
-	 * Builds a Structured Content Mode marshaller to marshal cloud event as JSON for
-	 * HTTP Transport Binding
-	 * @param <T> The 'data' type
-	 * @return A step to provider the {@link CloudEventImpl} and marshal as JSON
-	 * @see StructuredMarshaller
-	 */
-	public static <T> EventStep<AttributesImpl, T, String, String> structured() {
-		return 
-		StructuredMarshaller.
-		  <AttributesImpl, T, String, String>builder()
-			.mime("Content-Type", "application/cloudevents+json")
-			.map((event) -> {
-				return Json.<CloudEvent<AttributesImpl, T>, String>
-							marshaller().marshal(event, NO_HEADERS);
-			})
-			.map(Accessor::extensionsOf)
-			.map(ExtensionFormat::marshal)
-			.map(HeaderMapper::map);
-	}
-}
diff --git a/api/src/main/java/io/cloudevents/v03/http/Unmarshallers.java b/api/src/main/java/io/cloudevents/v03/http/Unmarshallers.java
deleted file mode 100644
index b40ca81e..00000000
--- a/api/src/main/java/io/cloudevents/v03/http/Unmarshallers.java
+++ /dev/null
@@ -1,123 +0,0 @@
-/**
- * Copyright 2019 The CloudEvents Authors
- *
- * 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
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * 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.v03.http;
-
-import javax.validation.Validator;
-
-import io.cloudevents.extensions.DistributedTracingExtension;
-import io.cloudevents.format.BinaryUnmarshaller;
-import io.cloudevents.format.StructuredUnmarshaller;
-import io.cloudevents.format.builder.HeadersStep;
-import io.cloudevents.json.Json;
-import io.cloudevents.v03.AttributesImpl;
-import io.cloudevents.v03.CloudEventBuilder;
-import io.cloudevents.v03.CloudEventImpl;
-
-/**
- * 
- * @author fabiojose
- * @version 0.3
- */
-public class Unmarshallers {
-	private Unmarshallers() {}
-
-	/**
-	 * Builds a Binary Content Mode unmarshaller to unmarshal JSON as CloudEvents data
-	 * for HTTP Transport Binding
-	 *
-	 * @param <T> The 'data' type
-	 * @param type The type reference to use for 'data' unmarshal
-	 * @return A step to supply the headers, payload and to unmarshal
-	 * @see BinaryUnmarshaller
-	 */
-	public static <T> HeadersStep<AttributesImpl, T, String>
-			binary(Class<T> type) {
-		return binary(type, null);
-	}
-
-	/**
-	 * Builds a Binary Content Mode unmarshaller to unmarshal JSON as CloudEvents data
-	 * for HTTP Transport Binding
-	 * 
-	 * @param <T> The 'data' type
-	 * @param type The type reference to use for 'data' unmarshal
-	 * @param validator Provided instance of a {@link Validator}
-	 * @return A step to supply the headers, payload and to unmarshal
-	 * @see BinaryUnmarshaller
-	 */
-	public static <T> HeadersStep<AttributesImpl, T, String> 
-			binary(Class<T> type, Validator validator) {
-		return 
-			BinaryUnmarshaller.<AttributesImpl, T, String>builder()
-				.map(AttributeMapper::map)
-				.map(AttributesImpl::unmarshal)
-				.map("application/json", Json.umarshaller(type)::unmarshal)
-				.next()
-				.map(ExtensionMapper::map)
-				.map(DistributedTracingExtension::unmarshall)
-				.next()
-				.builder(CloudEventBuilder.<T>builder().withValidator(validator)::build);
-	}
-
-	/**
-	 * Builds a Structured Content Mode unmarshaller to unmarshal JSON as CloudEvents data
-	 * for HTTP Transport Binding
-	 *
-	 * @param <T> The 'data' type
-	 * @param typeOfData The type reference to use for 'data' unmarshal
-	 * @return A step to supply the headers, payload and to unmarshal
-	 * @see StructuredUnmarshaller
-	 */
-	public static <T> HeadersStep<AttributesImpl, T, String>
-	structured(Class<T> typeOfData) {
-		return structured(typeOfData, null);
-	}
-
-	/**
-	 * Builds a Structured Content Mode unmarshaller to unmarshal JSON as CloudEvents data
-	 * for HTTP Transport Binding
-	 * 
-	 * @param <T> The 'data' type
-	 * @param typeOfData The type reference to use for 'data' unmarshal
-	 * @param validator Provided instance of a {@link Validator}
-	 * @return A step to supply the headers, payload and to unmarshal
-	 * @see StructuredUnmarshaller
-	 */
-	public static <T> HeadersStep<AttributesImpl, T, String> 
-			structured(Class<T> typeOfData, Validator validator) {
-		
-		return
-		StructuredUnmarshaller.<AttributesImpl, T, String>
-		  builder()
-			.map(ExtensionMapper::map)
-			.map(DistributedTracingExtension::unmarshall)
-			.next()
-			.map((payload, extensions) -> {			
-				CloudEventImpl<T> event =
-					Json.<CloudEventImpl<T>>
-						decodeValue(payload, CloudEventImpl.class, typeOfData);
-				
-				CloudEventBuilder<T> builder = 
-					CloudEventBuilder.<T>builder(event);
-				
-				extensions.get().forEach(extension -> {
-					builder.withExtension(extension);
-				});
-				
-				return builder.withValidator(validator).build();
-			});
-	}
-}
diff --git a/api/src/main/java/io/cloudevents/v1/AttributesImpl.java b/api/src/main/java/io/cloudevents/v1/AttributesImpl.java
index 6a4f492d..73ea5cda 100644
--- a/api/src/main/java/io/cloudevents/v1/AttributesImpl.java
+++ b/api/src/main/java/io/cloudevents/v1/AttributesImpl.java
@@ -31,17 +31,11 @@ import java.util.Optional;
 public class AttributesImpl implements Attributes {
 
 	private final String id;
-
 	private final URI source;
-
 	private final String type;
-
 	private final String datacontenttype;
-
 	private final URI dataschema;
-
 	private final String subject;
-
 	private final ZonedDateTime time;
 
 	public AttributesImpl(String id, URI source,
@@ -91,7 +85,25 @@ public class AttributesImpl implements Attributes {
 		return Optional.ofNullable(time);
 	}
 
-	@Override
+    @Override
+    public Attributes toV03() {
+        return new io.cloudevents.v03.AttributesImpl(
+            this.id,
+            this.source,
+            this.type,
+            this.time,
+            this.dataschema,
+            this.datacontenttype,
+            this.subject
+        );
+    }
+
+    @Override
+    public Attributes toV1() {
+        return this;
+    }
+
+    @Override
 	public String toString() {
 		return "Attibutes V1.0 [id=" + id + ", source=" + source
 				+ ", type=" + type
diff --git a/api/src/main/java/io/cloudevents/v1/CloudEventBuilder.java b/api/src/main/java/io/cloudevents/v1/CloudEventBuilder.java
index bde664da..fa0ee921 100644
--- a/api/src/main/java/io/cloudevents/v1/CloudEventBuilder.java
+++ b/api/src/main/java/io/cloudevents/v1/CloudEventBuilder.java
@@ -1,5 +1,7 @@
 package io.cloudevents.v1;
 
+import io.cloudevents.Attributes;
+import io.cloudevents.CloudEvent;
 import io.cloudevents.impl.BaseCloudEventBuilder;
 
 import java.net.URI;
@@ -15,7 +17,6 @@ public final class CloudEventBuilder extends BaseCloudEventBuilder<CloudEventBui
 
 	private String id;
 	private URI source;
-
 	private String type;
 	private String datacontenttype;
 	private URI dataschema;
@@ -26,6 +27,23 @@ public final class CloudEventBuilder extends BaseCloudEventBuilder<CloudEventBui
         super();
     }
 
+    public CloudEventBuilder(CloudEvent event) {
+        super(event);
+    }
+
+    @Override
+    protected void setAttributes(Attributes attributes) {
+        AttributesImpl attr = (AttributesImpl) attributes.toV1();
+        this
+            .withId(attr.getId())
+            .withSource(attr.getSource())
+            .withType(attr.getType());
+        attr.getDataContentType().ifPresent(this::withDataContentType);
+        attr.getDataSchema().ifPresent(this::withDataSchema);
+        attr.getSubject().ifPresent(this::withSubject);
+        attr.getTime().ifPresent(this::withTime);
+    }
+
     public CloudEventBuilder withId(String id) {
 		this.id = id;
 		return this;
diff --git a/api/src/main/java/io/cloudevents/v1/http/AttributeMapper.java b/api/src/main/java/io/cloudevents/v1/http/AttributeMapper.java
deleted file mode 100644
index 344b03ee..00000000
--- a/api/src/main/java/io/cloudevents/v1/http/AttributeMapper.java
+++ /dev/null
@@ -1,80 +0,0 @@
-/**
- * Copyright 2019 The CloudEvents Authors
- *
- * 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
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * 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.v1.http;
-
-import static java.util.stream.Collectors.toMap;
-
-import java.util.Locale;
-import java.util.Map;
-import java.util.Objects;
-import java.util.Optional;
-import java.util.AbstractMap.SimpleEntry;
-import java.util.Map.Entry;
-import java.util.concurrent.atomic.AtomicReference;
-
-import io.cloudevents.fun.BinaryFormatAttributeMapper;
-import io.cloudevents.v1.ContextAttributes;
-
-/**
- *
- * @author fabiojose
- * @version 1.0
- */
-public class AttributeMapper {
-	private AttributeMapper() {}
-
-	static final String HEADER_PREFIX = "ce-";
-
-	/**
-	 * Following the signature of {@link BinaryFormatAttributeMapper#map(Map)}
-	 * @param headers Map of HTTP request
-	 * @return Map with spec attributes and values without parsing
-	 * @see ContextAttributes
-	 */
-	public static Map<String, String> map(final Map<String, Object> headers) {
-		Objects.requireNonNull(headers);
-
-		final AtomicReference<Optional<Entry<String, Object>>> ct =
-				new AtomicReference<>();
-
-		ct.set(Optional.empty());
-
-		Map<String, String> result = headers.entrySet()
-			.stream()
-			.filter(header -> null!= header.getValue())
-			.map(header -> new SimpleEntry<>(header.getKey()
-					.toLowerCase(Locale.US), header.getValue()))
-			.peek(header -> {
-				if("content-type".equals(header.getKey())) {
-					ct.set(Optional.ofNullable(header));
-				}
-			})
-			.filter(header -> header.getKey().startsWith(HEADER_PREFIX))
-			.map(header -> new SimpleEntry<>(header.getKey()
-					.substring(HEADER_PREFIX.length()), header.getValue()))
-			.map(header -> new SimpleEntry<>(header.getKey(),
-					header.getValue().toString()))
-			.collect(toMap(Entry::getKey, Entry::getValue));
-
-		ct.get().ifPresent(contentType -> {
-			result.put(ContextAttributes.DATACONTENTTYPE.name(),
-					contentType.getValue().toString());
-		});
-
-		return result;
-	}
-
-}
diff --git a/api/src/main/java/io/cloudevents/v1/http/ExtensionMapper.java b/api/src/main/java/io/cloudevents/v1/http/ExtensionMapper.java
deleted file mode 100644
index ff4c7a28..00000000
--- a/api/src/main/java/io/cloudevents/v1/http/ExtensionMapper.java
+++ /dev/null
@@ -1,50 +0,0 @@
-package io.cloudevents.v1.http;
-
-import java.util.List;
-import java.util.Locale;
-import java.util.Map;
-import java.util.Objects;
-import java.util.AbstractMap.SimpleEntry;
-import java.util.Map.Entry;
-import java.util.stream.Collectors;
-
-import io.cloudevents.fun.FormatExtensionMapper;
-import io.cloudevents.v1.ContextAttributes;
-import io.cloudevents.v1.http.AttributeMapper;
-
-/**
- * 
- * @author fabiojose
- * @version 1.0
- */
-public class ExtensionMapper {
-	private ExtensionMapper() {}
-
-	private static final List<String> RESERVED_HEADERS = 
-			ContextAttributes.VALUES.stream()
-				.map(attribute -> AttributeMapper
-						.HEADER_PREFIX + attribute)
-				.collect(Collectors.toList());
-		static {
-			RESERVED_HEADERS.add("content-type");
-		};
-
-	/**
-	 * Following the signature of {@link FormatExtensionMapper}
-	 * @param headers The HTTP headers
-	 * @return The potential extensions without parsing
-	 */
-	public static Map<String, String> map(Map<String, Object> headers) {
-		Objects.requireNonNull(headers);
-		
-		// remove all reserved words and the remaining may be extensions
-		return 
-		headers.entrySet()
-			.stream()
-			.filter(header -> null!= header.getValue())
-			.map(header -> new SimpleEntry<>(header.getKey()
-					.toLowerCase(Locale.US), header.getValue().toString()))
-			.filter(header -> !RESERVED_HEADERS.contains(header.getKey()))
-			.collect(Collectors.toMap(Entry::getKey, Entry::getValue));
-	}
-}
diff --git a/api/src/main/java/io/cloudevents/v1/http/HeaderMapper.java b/api/src/main/java/io/cloudevents/v1/http/HeaderMapper.java
deleted file mode 100644
index 201ff895..00000000
--- a/api/src/main/java/io/cloudevents/v1/http/HeaderMapper.java
+++ /dev/null
@@ -1,79 +0,0 @@
-/**
- * Copyright 2019 The CloudEvents Authors
- *
- * 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
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * 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.v1.http;
-
-import static io.cloudevents.v1.http.AttributeMapper.HEADER_PREFIX;
-
-import java.util.Locale;
-import java.util.Map;
-import java.util.Objects;
-import java.util.Optional;
-import java.util.AbstractMap.SimpleEntry;
-import java.util.Map.Entry;
-import java.util.stream.Collectors;
-
-import io.cloudevents.fun.FormatHeaderMapper;
-import io.cloudevents.v1.ContextAttributes;
-
-/**
- *
- * @author fabiojose
- *
- */
-public class HeaderMapper {
-	private HeaderMapper() {}
-
-	private static final String HTTP_CONTENT_TYPE = "Content-Type";
-
-	/**
-	 * Following the signature of {@link FormatHeaderMapper}
-	 * @param attributes The map of attributes created by {@link AttributeMapper}
-	 * @param extensions The map of extensions created by {@link ExtensionMapper}
-	 * @return The map of HTTP Headers
-	 */
-	public static Map<String, String> map(Map<String, String> attributes,
-			Map<String, String> extensions) {
-		Objects.requireNonNull(attributes);
-		Objects.requireNonNull(extensions);
-
-		Map<String, String> result = attributes.entrySet()
-			.stream()
-			.filter(attribute -> null!= attribute.getValue())
-			.map(header -> new SimpleEntry<>(header.getKey()
-					.toLowerCase(Locale.US), header.getValue()))
-			.filter(header -> !header.getKey()
-					.equals(ContextAttributes.DATACONTENTTYPE.name()))
-			.map(header -> new SimpleEntry<>(HEADER_PREFIX + header.getKey(),
-					header.getValue()))
-			.collect(Collectors.toMap(Entry::getKey, Entry::getValue));
-
-		result.putAll(
-			extensions.entrySet()
-				.stream()
-				.filter(extension -> null != extension.getValue())
-				.collect(Collectors.toMap(Entry::getKey, Entry::getValue))
-		);
-
-		Optional.ofNullable(attributes
-				.get(ContextAttributes.DATACONTENTTYPE.name()))
-			.ifPresent((dct) -> {
-				result.put(HTTP_CONTENT_TYPE, dct);
-			});
-
-		return result;
-	}
-
-}
diff --git a/api/src/main/java/io/cloudevents/v1/http/Marshallers.java b/api/src/main/java/io/cloudevents/v1/http/Marshallers.java
deleted file mode 100644
index 1bb8a69f..00000000
--- a/api/src/main/java/io/cloudevents/v1/http/Marshallers.java
+++ /dev/null
@@ -1,67 +0,0 @@
-package io.cloudevents.v1.http;
-
-import java.util.HashMap;
-import java.util.Map;
-
-import io.cloudevents.CloudEvent;
-import io.cloudevents.extensions.ExtensionFormat;
-import io.cloudevents.format.BinaryMarshaller;
-import io.cloudevents.format.StructuredMarshaller;
-import io.cloudevents.format.Wire;
-import io.cloudevents.format.builder.EventStep;
-import io.cloudevents.json.Json;
-import io.cloudevents.v1.Accessor;
-import io.cloudevents.v1.AttributesImpl;
-import io.cloudevents.v1.CloudEventImpl;
-import io.cloudevents.v1.http.HeaderMapper;
-
-/**
- * 
- * @author fabiojose
- * @version 1.0
- */
-public class Marshallers {
-	private Marshallers() {}
-	
-	private static final Map<String, String> NO_HEADERS =
-			new HashMap<String, String>();
-		
-	/**
-	 * Builds a Binary Content Mode marshaller to marshal cloud events as JSON for
-	 * HTTP Transport Binding
-	 * 
-	 * @param <T> The 'data' type
-	 * @return A step to provide the {@link CloudEventImpl} and marshal as JSON
-	 * @see BinaryMarshaller
-	 */
-	public static <T> EventStep<AttributesImpl, T, String, String> binary() {
-		return 
-			BinaryMarshaller.<AttributesImpl, T, String, String>
-			  builder()
-				.map(AttributesImpl::marshal)
-				.map(Accessor::extensionsOf)
-				.map(ExtensionFormat::marshal)
-				.map(HeaderMapper::map)
-				.map(Json.<T, String>marshaller()::marshal)
-				.builder(Wire::new);
-	}
-	
-	/**
-	 * Builds a Structured Content Mode marshaller to marshal cloud event as JSON for
-	 * HTTP Transport Binding
-	 * @param <T> The 'data' type
-	 * @return A step to provider the {@link CloudEventImpl} and marshal as JSON
-	 * @see StructuredMarshaller
-	 */
-	public static <T> EventStep<AttributesImpl, T, String, String> structured() {
-		return 
-		StructuredMarshaller.
-		  <AttributesImpl, T, String, String>builder()
-			.mime("Content-Type", "application/cloudevents+json")
-			.map((event) -> Json.<CloudEvent<AttributesImpl, T>, String>
-						marshaller().marshal(event, NO_HEADERS))
-			.map(Accessor::extensionsOf)
-			.map(ExtensionFormat::marshal)
-			.map(HeaderMapper::map);
-	}
-}
diff --git a/api/src/main/java/io/cloudevents/v1/http/Unmarshallers.java b/api/src/main/java/io/cloudevents/v1/http/Unmarshallers.java
deleted file mode 100644
index 90412c32..00000000
--- a/api/src/main/java/io/cloudevents/v1/http/Unmarshallers.java
+++ /dev/null
@@ -1,122 +0,0 @@
-/**
- * Copyright 2019 The CloudEvents Authors
- *
- * 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
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * 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.v1.http;
-
-import javax.validation.Validator;
-
-import io.cloudevents.extensions.DistributedTracingExtension;
-import io.cloudevents.format.BinaryUnmarshaller;
-import io.cloudevents.format.StructuredUnmarshaller;
-import io.cloudevents.format.builder.HeadersStep;
-import io.cloudevents.json.Json;
-import io.cloudevents.v1.AttributesImpl;
-import io.cloudevents.v1.CloudEventBuilder;
-import io.cloudevents.v1.CloudEventImpl;
-
-/**
- * 
- * @author fabiojose
- * @version 1.0
- */
-public class Unmarshallers {
-	private Unmarshallers() {}
-
-	/**
-	 * Builds a Binary Content Mode unmarshaller to unmarshal JSON as CloudEvents data
-	 * for HTTP Transport Binding
-	 *
-	 * @param <T> The 'data' type
-	 * @param type The type reference to use for 'data' unmarshal
-	 * @return A step to supply the headers, payload and to unmarshal
-	 * @see BinaryUnmarshaller
-	 */
-	public static <T> HeadersStep<AttributesImpl, T, String>
-			binary(Class<T> type) {
-		return binary(type, null);
-	}
-
-	/**
-	 * Builds a Binary Content Mode unmarshaller to unmarshal JSON as CloudEvents data
-	 * for HTTP Transport Binding
-	 *
-	 * @param <T> The 'data' type
-	 * @param type The type reference to use for 'data' unmarshal
-	 * @param validator Provided instance of a {@link Validator}
-	 * @return A step to supply the headers, payload and to unmarshal
-	 * @see BinaryUnmarshaller
-	 */
-	public static <T> HeadersStep<AttributesImpl, T, String> 
-			binary(Class<T> type, Validator validator) {
-		return 
-			BinaryUnmarshaller.<AttributesImpl, T, String>builder()
-				.map(AttributeMapper::map)
-				.map(AttributesImpl::unmarshal)
-				.map("application/json", Json.umarshaller(type)::unmarshal)
-				.next()
-				.map(ExtensionMapper::map)
-				.map(DistributedTracingExtension::unmarshall)
-				.next()
-				.builder(CloudEventBuilder.<T>builder().withValidator(validator)::build);
-	}
-	
-	/**
-	 * Builds a Structured Content Mode unmarshaller to unmarshal JSON as CloudEvents data
-	 * for HTTP Transport Binding
-	 * 
-	 * @param <T> The 'data' type
-	 * @param typeOfData The type reference to use for 'data' unmarshal
-	 * @return A step to supply the headers, payload and to unmarshal
-	 * @see StructuredUnmarshaller
-	 */
-	public static <T> HeadersStep<AttributesImpl, T, String> 
-			structured(Class<T> typeOfData) {
-		return structured(typeOfData, null);
-	}
-
-		/**
-		 * Builds a Structured Content Mode unmarshaller to unmarshal JSON as CloudEvents data
-		 * for HTTP Transport Binding
-		 *
-		 * @param <T> The 'data' type
-		 * @param typeOfData The type reference to use for 'data' unmarshal
-		 * @param validator Provided instance of a {@link Validator}
-		 * @return A step to supply the headers, payload and to unmarshal
-		 * @see StructuredUnmarshaller
-		 */
-		public static <T> HeadersStep<AttributesImpl, T, String>
-			structured(Class<T> typeOfData, Validator validator) {
-		return
-		StructuredUnmarshaller.<AttributesImpl, T, String>
-		  builder()
-			.map(ExtensionMapper::map)
-			.map(DistributedTracingExtension::unmarshall)
-			.next()
-			.map((payload, extensions) -> {			
-				CloudEventImpl<T> event =
-					Json.<CloudEventImpl<T>>
-						decodeValue(payload, CloudEventImpl.class, typeOfData);
-				
-				CloudEventBuilder<T> builder = 
-					CloudEventBuilder.<T>builder(event);
-				
-				extensions.get().forEach(extension -> {
-					builder.withExtension(extension);
-				});
-
-				return builder.withValidator(validator).build();
-			});
-	}
-}
diff --git a/api/src/test/java/io/cloudevents/extensions/DistributedTracingExtensionTest.java b/api/src/test/java/io/cloudevents/extensions/DistributedTracingExtensionTest.java
index e58cbc7d..f277191d 100644
--- a/api/src/test/java/io/cloudevents/extensions/DistributedTracingExtensionTest.java
+++ b/api/src/test/java/io/cloudevents/extensions/DistributedTracingExtensionTest.java
@@ -33,8 +33,7 @@ public class DistributedTracingExtensionTest {
 		tracing.setTraceparent("parent");
 		tracing.setTracestate("state");
 
-        CloudEvent event = CloudEvent.build().build();
-        tracing.writeToEvent(event);
+        CloudEvent event = CloudEvent.buildV1().withExtension(tracing).build();
 
         assertThat(event.getExtensions())
             .containsEntry(DistributedTracingExtension.TRACEPARENT, "parent")
@@ -43,7 +42,7 @@ public class DistributedTracingExtensionTest {
 
 	@Test
 	public void parseExtension() {
-        CloudEvent event = CloudEvent.build()
+        CloudEvent event = CloudEvent.buildV1()
             .withExtension(DistributedTracingExtension.TRACEPARENT, "parent")
             .withExtension(DistributedTracingExtension.TRACESTATE, "state")
             .build();