diff --git a/api/all/src/main/java/io/opentelemetry/api/baggage/propagation/W3CBaggagePropagator.java b/api/all/src/main/java/io/opentelemetry/api/baggage/propagation/W3CBaggagePropagator.java
index 198a0d656f..e2ff915eba 100644
--- a/api/all/src/main/java/io/opentelemetry/api/baggage/propagation/W3CBaggagePropagator.java
+++ b/api/all/src/main/java/io/opentelemetry/api/baggage/propagation/W3CBaggagePropagator.java
@@ -40,7 +40,7 @@ public final class W3CBaggagePropagator implements TextMapPropagator {
   }
 
   @Override
-  public <C> void inject(Context context, C carrier, TextMapSetter<C> setter) {
+  public <C> void inject(Context context, @Nullable C carrier, TextMapSetter<C> setter) {
     if (context == null || setter == null) {
       return;
     }
diff --git a/api/all/src/main/java/io/opentelemetry/api/common/ArrayBackedAttributes.java b/api/all/src/main/java/io/opentelemetry/api/common/ArrayBackedAttributes.java
index 0242a1b2d3..da0c3c7f57 100644
--- a/api/all/src/main/java/io/opentelemetry/api/common/ArrayBackedAttributes.java
+++ b/api/all/src/main/java/io/opentelemetry/api/common/ArrayBackedAttributes.java
@@ -8,6 +8,7 @@ package io.opentelemetry.api.common;
 import io.opentelemetry.api.internal.ImmutableKeyValuePairs;
 import java.util.ArrayList;
 import java.util.Comparator;
+import javax.annotation.Nullable;
 import javax.annotation.concurrent.Immutable;
 
 @Immutable
@@ -32,6 +33,7 @@ final class ArrayBackedAttributes extends ImmutableKeyValuePairs<AttributeKey<?>
 
   @SuppressWarnings("unchecked")
   @Override
+  @Nullable
   public <T> T get(AttributeKey<T> key) {
     return (T) super.get(key);
   }
diff --git a/api/all/src/main/java/io/opentelemetry/api/common/ArrayBackedAttributesBuilder.java b/api/all/src/main/java/io/opentelemetry/api/common/ArrayBackedAttributesBuilder.java
index 7fcc841911..9c2918d6e1 100644
--- a/api/all/src/main/java/io/opentelemetry/api/common/ArrayBackedAttributesBuilder.java
+++ b/api/all/src/main/java/io/opentelemetry/api/common/ArrayBackedAttributesBuilder.java
@@ -8,7 +8,6 @@ package io.opentelemetry.api.common;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
-import javax.annotation.Nullable;
 
 class ArrayBackedAttributesBuilder implements AttributesBuilder {
   private final List<Object> data;
@@ -53,11 +52,7 @@ class ArrayBackedAttributesBuilder implements AttributesBuilder {
     return this;
   }
 
-  @Nullable
-  static List<Double> toList(@Nullable double... values) {
-    if (values == null) {
-      return null;
-    }
+  static List<Double> toList(double... values) {
     Double[] boxed = new Double[values.length];
     for (int i = 0; i < values.length; i++) {
       boxed[i] = values[i];
@@ -65,11 +60,7 @@ class ArrayBackedAttributesBuilder implements AttributesBuilder {
     return Arrays.asList(boxed);
   }
 
-  @Nullable
-  static List<Long> toList(@Nullable long... values) {
-    if (values == null) {
-      return null;
-    }
+  static List<Long> toList(long... values) {
     Long[] boxed = new Long[values.length];
     for (int i = 0; i < values.length; i++) {
       boxed[i] = values[i];
@@ -77,11 +68,7 @@ class ArrayBackedAttributesBuilder implements AttributesBuilder {
     return Arrays.asList(boxed);
   }
 
-  @Nullable
-  static List<Boolean> toList(@Nullable boolean... values) {
-    if (values == null) {
-      return null;
-    }
+  static List<Boolean> toList(boolean... values) {
     Boolean[] boxed = new Boolean[values.length];
     for (int i = 0; i < values.length; i++) {
       boxed[i] = values[i];
diff --git a/api/all/src/main/java/io/opentelemetry/api/common/AttributeKeyImpl.java b/api/all/src/main/java/io/opentelemetry/api/common/AttributeKeyImpl.java
index 691b31a56a..2e67911d63 100644
--- a/api/all/src/main/java/io/opentelemetry/api/common/AttributeKeyImpl.java
+++ b/api/all/src/main/java/io/opentelemetry/api/common/AttributeKeyImpl.java
@@ -29,12 +29,7 @@ abstract class AttributeKeyImpl<T> implements AttributeKey<T> {
   }
 
   @Override
-  public String getKey() {
-    return key();
-  }
-
-  @Nullable
-  abstract String key();
+  public abstract String getKey();
 
   @Override
   public final String toString() {
diff --git a/api/all/src/main/java/io/opentelemetry/api/common/Attributes.java b/api/all/src/main/java/io/opentelemetry/api/common/Attributes.java
index db59fc34c4..418d679316 100644
--- a/api/all/src/main/java/io/opentelemetry/api/common/Attributes.java
+++ b/api/all/src/main/java/io/opentelemetry/api/common/Attributes.java
@@ -9,6 +9,7 @@ import static io.opentelemetry.api.common.ArrayBackedAttributes.sortAndFilterToA
 
 import java.util.Map;
 import java.util.function.BiConsumer;
+import javax.annotation.Nullable;
 import javax.annotation.concurrent.Immutable;
 
 /**
@@ -33,6 +34,7 @@ import javax.annotation.concurrent.Immutable;
 public interface Attributes {
 
   /** Returns the value for the given {@link AttributeKey}, or {@code null} if not found. */
+  @Nullable
   <T> T get(AttributeKey<T> key);
 
   /** Iterates over all the key-value pairs of attributes contained by this instance. */
diff --git a/api/all/src/main/java/io/opentelemetry/api/common/AttributesBuilder.java b/api/all/src/main/java/io/opentelemetry/api/common/AttributesBuilder.java
index 757f05e967..16f29c2540 100644
--- a/api/all/src/main/java/io/opentelemetry/api/common/AttributesBuilder.java
+++ b/api/all/src/main/java/io/opentelemetry/api/common/AttributesBuilder.java
@@ -85,7 +85,10 @@ public interface AttributesBuilder {
    * @return this Builder
    */
   default AttributesBuilder put(String key, String... value) {
-    return put(stringArrayKey(key), value == null ? null : Arrays.asList(value));
+    if (value == null) {
+      return this;
+    }
+    return put(stringArrayKey(key), Arrays.asList(value));
   }
 
   /**
@@ -97,6 +100,9 @@ public interface AttributesBuilder {
    * @return this Builder
    */
   default AttributesBuilder put(String key, long... value) {
+    if (value == null) {
+      return this;
+    }
     return put(longArrayKey(key), toList(value));
   }
 
@@ -109,6 +115,9 @@ public interface AttributesBuilder {
    * @return this Builder
    */
   default AttributesBuilder put(String key, double... value) {
+    if (value == null) {
+      return this;
+    }
     return put(doubleArrayKey(key), toList(value));
   }
 
@@ -121,6 +130,9 @@ public interface AttributesBuilder {
    * @return this Builder
    */
   default AttributesBuilder put(String key, boolean... value) {
+    if (value == null) {
+      return this;
+    }
     return put(booleanArrayKey(key), toList(value));
   }
 
diff --git a/api/all/src/main/java/io/opentelemetry/api/internal/ReadOnlyArrayMap.java b/api/all/src/main/java/io/opentelemetry/api/internal/ReadOnlyArrayMap.java
index 6bb840353d..d4f27959f7 100644
--- a/api/all/src/main/java/io/opentelemetry/api/internal/ReadOnlyArrayMap.java
+++ b/api/all/src/main/java/io/opentelemetry/api/internal/ReadOnlyArrayMap.java
@@ -29,6 +29,7 @@ import java.util.List;
 import java.util.Map;
 import java.util.NoSuchElementException;
 import java.util.Set;
+import javax.annotation.Nullable;
 
 /** A read-only view of an array of key-value pairs. */
 @SuppressWarnings("unchecked")
@@ -74,6 +75,7 @@ public final class ReadOnlyArrayMap<K, V> extends AbstractMap<K, V> {
   }
 
   @Override
+  @Nullable
   public V get(Object o) {
     if (o == null) {
       return null; // null keys are not allowed
diff --git a/api/all/src/main/java/io/opentelemetry/api/trace/ArrayBasedTraceStateBuilder.java b/api/all/src/main/java/io/opentelemetry/api/trace/ArrayBasedTraceStateBuilder.java
index fb952346ab..987b28bada 100644
--- a/api/all/src/main/java/io/opentelemetry/api/trace/ArrayBasedTraceStateBuilder.java
+++ b/api/all/src/main/java/io/opentelemetry/api/trace/ArrayBasedTraceStateBuilder.java
@@ -25,19 +25,18 @@ final class ArrayBasedTraceStateBuilder implements TraceStateBuilder {
   private static final int VALUE_MAX_SIZE = 256;
   private static final int MAX_TENANT_ID_SIZE = 240;
 
-  private final ArrayBasedTraceState parent;
-  @Nullable private List<String> entries;
+  private final List<String> entries;
 
   static TraceState empty() {
     return EMPTY;
   }
 
   ArrayBasedTraceStateBuilder() {
-    parent = EMPTY;
+    entries = new ArrayList<>();
   }
 
   ArrayBasedTraceStateBuilder(ArrayBasedTraceState parent) {
-    this.parent = parent;
+    entries = new ArrayList<>(parent.getEntries());
   }
 
   /**
@@ -57,10 +56,6 @@ final class ArrayBasedTraceStateBuilder implements TraceStateBuilder {
         || (entries != null && entries.size() >= MAX_KEY_VALUE_PAIRS)) {
       return this;
     }
-    if (entries == null) {
-      // Copy entries from the parent.
-      entries = new ArrayList<>(parent.getEntries());
-    }
     removeEntry(key);
     // Inserts the element at the front of this list. (note: probably pretty inefficient with an
     // ArrayList as the underlying implementation!)
@@ -74,10 +69,6 @@ final class ArrayBasedTraceStateBuilder implements TraceStateBuilder {
     if (key == null) {
       return this;
     }
-    if (entries == null) {
-      // Copy entries from the parent.
-      entries = new ArrayList<>(parent.getEntries());
-    }
     removeEntry(key);
     return this;
   }
@@ -97,9 +88,6 @@ final class ArrayBasedTraceStateBuilder implements TraceStateBuilder {
 
   @Override
   public TraceState build() {
-    if (entries == null) {
-      return parent;
-    }
     return ArrayBasedTraceState.create(entries);
   }
 
diff --git a/api/all/src/main/java/io/opentelemetry/api/trace/DefaultTracerProvider.java b/api/all/src/main/java/io/opentelemetry/api/trace/DefaultTracerProvider.java
index 2b465ea415..ec300a420e 100644
--- a/api/all/src/main/java/io/opentelemetry/api/trace/DefaultTracerProvider.java
+++ b/api/all/src/main/java/io/opentelemetry/api/trace/DefaultTracerProvider.java
@@ -18,7 +18,7 @@ class DefaultTracerProvider implements TracerProvider {
 
   @Override
   public Tracer get(String instrumentationName) {
-    return get(instrumentationName, null);
+    return DefaultTracer.getInstance();
   }
 
   @Override
diff --git a/build.gradle.kts b/build.gradle.kts
index fd51c05ec3..1438c1f9dd 100644
--- a/build.gradle.kts
+++ b/build.gradle.kts
@@ -5,8 +5,10 @@ import io.morethan.jmhreport.gradle.JmhReportExtension
 import me.champeau.gradle.JMHPluginExtension
 import me.champeau.gradle.japicmp.JapicmpTask
 import nebula.plugin.release.git.opinion.Strategies
+import net.ltgt.gradle.errorprone.CheckSeverity
 import net.ltgt.gradle.errorprone.ErrorProneOptions
 import net.ltgt.gradle.errorprone.ErrorPronePlugin
+import net.ltgt.gradle.nullaway.NullAwayOptions
 import org.gradle.api.plugins.JavaPlugin.*
 import org.gradle.api.tasks.testing.logging.TestExceptionFormat
 import ru.vyarus.gradle.plugin.animalsniffer.AnimalSnifferExtension
@@ -24,6 +26,7 @@ plugins {
     id("io.morethan.jmhreport") apply false
     id("me.champeau.gradle.jmh") apply false
     id("net.ltgt.errorprone") apply false
+    id("net.ltgt.nullaway") apply false
     id("ru.vyarus.animalsniffer") apply false
     id("me.champeau.gradle.japicmp") apply false
 }
@@ -103,6 +106,8 @@ nexusStaging {
     delayBetweenRetriesInMillis = 10000
 }
 
+val enableNullaway: String? by project
+
 subprojects {
     group = "io.opentelemetry"
 
@@ -114,6 +119,7 @@ subprojects {
 
         plugins.apply("com.diffplug.spotless")
         plugins.apply("net.ltgt.errorprone")
+        plugins.apply("net.ltgt.nullaway")
 
         configure<BasePluginConvention> {
             archivesBaseName = "opentelemetry-${name}"
@@ -190,6 +196,17 @@ subprojects {
                     disableWarningsInGeneratedCode.set(true)
                     allDisabledChecksAsWarnings.set(true)
 
+                    (this as ExtensionAware).extensions.configure<NullAwayOptions> {
+                        // Enable nullaway on main sources.
+                        // TODO(anuraaga): Remove enableNullaway flag when all errors fixed
+                        if (!name.contains("Test") && !name.contains("Jmh") && enableNullaway == "true") {
+                            severity.set(CheckSeverity.ERROR)
+                        } else {
+                            severity.set(CheckSeverity.OFF)
+                        }
+                        annotatedPackages.add("io.opentelemetry")
+                    }
+
                     // Doesn't currently use Var annotations.
                     disable("Var") // "-Xep:Var:OFF"
 
@@ -208,7 +225,7 @@ subprojects {
                     disable("UnnecessarilyFullyQualified")
 
                     // Ignore warnings for protobuf and jmh generated files.
-                    excludedPaths.set(".*generated.*")
+                    excludedPaths.set(".*generated.*|.*internal.shaded.*")
                     // "-XepExcludedPaths:.*/build/generated/source/proto/.*"
 
                     disable("Java7ApiChecker")
@@ -375,6 +392,7 @@ subprojects {
             add(TEST_RUNTIME_ONLY_CONFIGURATION_NAME, "org.junit.vintage:junit-vintage-engine")
 
             add(ErrorPronePlugin.CONFIGURATION_NAME, "com.google.errorprone:error_prone_core")
+            add(ErrorPronePlugin.CONFIGURATION_NAME, "com.uber.nullaway:nullaway")
 
             add(ANNOTATION_PROCESSOR_CONFIGURATION_NAME, "com.google.guava:guava-beta-checker")
 
diff --git a/context/src/main/java/io/opentelemetry/context/StrictContextStorage.java b/context/src/main/java/io/opentelemetry/context/StrictContextStorage.java
index 1d52b5b8d1..87080f35a3 100644
--- a/context/src/main/java/io/opentelemetry/context/StrictContextStorage.java
+++ b/context/src/main/java/io/opentelemetry/context/StrictContextStorage.java
@@ -30,6 +30,7 @@ import java.util.concurrent.Executor;
 import java.util.logging.Level;
 import java.util.logging.Logger;
 import java.util.stream.Collectors;
+import javax.annotation.Nullable;
 
 /**
  * A {@link ContextStorage} which keeps track of opened and closed {@link Scope}s, reporting caller
@@ -112,6 +113,7 @@ final class StrictContextStorage implements ContextStorage, AutoCloseable {
   }
 
   @Override
+  @Nullable
   public Context current() {
     return delegate.current();
   }
@@ -209,7 +211,8 @@ final class StrictContextStorage implements ContextStorage, AutoCloseable {
 
     @Override
     public String toString() {
-      return caller.getMessage();
+      String message = caller.getMessage();
+      return message != null ? message : super.toString();
     }
   }
 
diff --git a/dependencyManagement/build.gradle.kts b/dependencyManagement/build.gradle.kts
index 6737f22cf2..b97ef8a659 100644
--- a/dependencyManagement/build.gradle.kts
+++ b/dependencyManagement/build.gradle.kts
@@ -80,6 +80,7 @@ val DEPENDENCIES = listOf(
         "com.squareup.okhttp3:okhttp:4.9.1",
         "com.sun.net.httpserver:http:20070405",
         "com.tngtech.archunit:archunit-junit4:0.17.0",
+        "com.uber.nullaway:nullaway:0.9.1",
         "edu.berkeley.cs.jqf:jqf-fuzz:1.6",
         "eu.rekawek.toxiproxy:toxiproxy-java:2.1.4",
         "io.github.netmikey.logunit:logunit-jul:1.1.0",
diff --git a/docs/apidiffs/current_vs_latest/opentelemetry-api.txt b/docs/apidiffs/current_vs_latest/opentelemetry-api.txt
index df26146497..031b54b48c 100644
--- a/docs/apidiffs/current_vs_latest/opentelemetry-api.txt
+++ b/docs/apidiffs/current_vs_latest/opentelemetry-api.txt
@@ -1,2 +1,5 @@
 Comparing source compatibility of  against 
-No changes.
\ No newline at end of file
+===  UNCHANGED INTERFACE: PUBLIC ABSTRACT io.opentelemetry.api.common.Attributes  (not serializable)
+	===  CLASS FILE FORMAT VERSION: 52.0 <- 52.0
+	===  UNCHANGED METHOD: PUBLIC ABSTRACT java.lang.Object get(io.opentelemetry.api.common.AttributeKey)
+		+++  NEW ANNOTATION: javax.annotation.Nullable
diff --git a/extensions/trace-propagators/src/main/java/io/opentelemetry/extension/trace/propagation/JaegerPropagator.java b/extensions/trace-propagators/src/main/java/io/opentelemetry/extension/trace/propagation/JaegerPropagator.java
index 37ea3b4680..93dce945b4 100644
--- a/extensions/trace-propagators/src/main/java/io/opentelemetry/extension/trace/propagation/JaegerPropagator.java
+++ b/extensions/trace-propagators/src/main/java/io/opentelemetry/extension/trace/propagation/JaegerPropagator.java
@@ -215,10 +215,13 @@ public final class JaegerPropagator implements TextMapPropagator {
     return buildSpanContext(traceId, spanId, flags);
   }
 
-  private static <C> Baggage getBaggageFromHeader(C carrier, TextMapGetter<C> getter) {
+  @Nullable
+  private static <C> Baggage getBaggageFromHeader(@Nullable C carrier, TextMapGetter<C> getter) {
     BaggageBuilder builder = null;
 
-    for (String key : getter.keys(carrier)) {
+    Iterable<String> keys = carrier != null ? getter.keys(carrier) : Collections.emptyList();
+
+    for (String key : keys) {
       if (key.startsWith(BAGGAGE_PREFIX)) {
         if (key.length() == BAGGAGE_PREFIX.length()) {
           continue;
@@ -227,9 +230,19 @@ public final class JaegerPropagator implements TextMapPropagator {
         if (builder == null) {
           builder = Baggage.builder();
         }
-        builder.put(key.substring(BAGGAGE_PREFIX.length()), getter.get(carrier, key));
+
+        String value = getter.get(carrier, key);
+        if (value != null) {
+          builder.put(key.substring(BAGGAGE_PREFIX.length()), value);
+        }
       } else if (key.equals(BAGGAGE_HEADER)) {
-        builder = parseBaggageHeader(getter.get(carrier, key), builder);
+        String value = getter.get(carrier, key);
+        if (value != null) {
+          if (builder == null) {
+            builder = Baggage.builder();
+          }
+          builder = parseBaggageHeader(value, builder);
+        }
       }
     }
     return builder == null ? null : builder.build();
@@ -239,9 +252,6 @@ public final class JaegerPropagator implements TextMapPropagator {
     for (String part : header.split("\\s*,\\s*")) {
       String[] kv = part.split("\\s*=\\s*");
       if (kv.length == 2) {
-        if (builder == null) {
-          builder = Baggage.builder();
-        }
         builder.put(kv[0], kv[1]);
       } else {
         logger.fine("malformed token in " + BAGGAGE_HEADER + " header: " + part);
diff --git a/settings.gradle.kts b/settings.gradle.kts
index 114d0711e7..3a79ffa905 100644
--- a/settings.gradle.kts
+++ b/settings.gradle.kts
@@ -12,6 +12,8 @@ pluginManagement {
         id("me.champeau.gradle.jmh") version "0.5.3"
         id("nebula.release") version "15.3.1"
         id("net.ltgt.errorprone") version "2.0.1"
+        id("net.ltgt.nullaway") version "1.1.0"
+        id("org.checkerframework") version "0.5.20"
         id("org.jetbrains.kotlin.jvm") version "1.4.21"
         id("org.unbroken-dome.test-sets") version "3.0.1"
         id("ru.vyarus.animalsniffer") version "1.5.3"