add Nullaway to instrumentation API

conventions/src/main/kotlin/otel.nullaway-conventions.gradle.kts

@@ -18,10 +18,19 @@ nullaway {
 
 tasks {
   withType<JavaCompile>().configureEach {
-    if (!name.contains("test", ignoreCase = true)) {
+    if (name.contains("test", ignoreCase = true)) {
+      options.errorprone.nullaway {
+        enabled = false
+      }
+    } else {
       options.errorprone.nullaway {
         severity.set(CheckSeverity.ERROR)
       }
     }
+    options.errorprone.nullaway {
+      customInitializerAnnotations.add("org.openjdk.jmh.annotations.Setup")
+      excludedFieldAnnotations.add("org.mockito.Mock")
+      excludedFieldAnnotations.add("org.mockito.InjectMocks")
+    }
   }
 }

instrumentation-api/build.gradle.kts

@@ -7,6 +7,7 @@ plugins {
   id("otel.japicmp-conventions")
   id("otel.publish-conventions")
   id("otel.jmh-conventions")
+  id("otel.nullaway-conventions")
 }
 
 group = "io.opentelemetry.instrumentation"

instrumentation-api/src/jmh/java/io/opentelemetry/instrumentation/api/instrumenter/InstrumenterBenchmark.java

@@ -33,8 +33,10 @@
 @State(Scope.Thread)
 public class InstrumenterBenchmark {
 
-  private static final Instrumenter<Void, Void> INSTRUMENTER =
-      Instrumenter.<Void, Void>builder(
+  private static final Object REQUEST = new Object();
+
+  private static final Instrumenter<Object, Void> INSTRUMENTER =
+      Instrumenter.<Object, Void>builder(
               OpenTelemetry.noop(),
               "benchmark",
               HttpSpanNameExtractor.create(ConstantHttpAttributesGetter.INSTANCE))
@@ -44,75 +46,76 @@ public class InstrumenterBenchmark {
 
   @Benchmark
   public Context start() {
-    return INSTRUMENTER.start(Context.root(), null);
+    return INSTRUMENTER.start(Context.root(), REQUEST);
   }
 
   @Benchmark
   public Context startEnd() {
-    Context context = INSTRUMENTER.start(Context.root(), null);
-    INSTRUMENTER.end(context, null, null, null);
+    Context context = INSTRUMENTER.start(Context.root(), REQUEST);
+    INSTRUMENTER.end(context, REQUEST, null, null);
     return context;
   }
 
-  enum ConstantHttpAttributesGetter implements HttpClientAttributesGetter<Void, Void> {
+  enum ConstantHttpAttributesGetter implements HttpClientAttributesGetter<Object, Void> {
     INSTANCE;
 
     private static final InetSocketAddress PEER_ADDRESS =
         InetSocketAddress.createUnresolved("localhost", 8080);
 
     @Override
-    public String getUrlFull(Void unused) {
+    public String getUrlFull(Object unused) {
       return "https://opentelemetry.io/benchmark";
     }
 
     @Override
-    public String getHttpRequestMethod(Void unused) {
+    public String getHttpRequestMethod(Object unused) {
       return "GET";
     }
 
     @Override
-    public List<String> getHttpRequestHeader(Void unused, String name) {
+    public List<String> getHttpRequestHeader(Object unused, String name) {
       if (name.equalsIgnoreCase("user-agent")) {
         return Collections.singletonList("OpenTelemetryBot");
       }
       return Collections.emptyList();
     }
 
     @Override
-    public Integer getHttpResponseStatusCode(Void unused, Void unused2, @Nullable Throwable error) {
+    public Integer getHttpResponseStatusCode(
+        Object unused, Void unused2, @Nullable Throwable error) {
       return 200;
     }
 
     @Override
-    public List<String> getHttpResponseHeader(Void unused, Void unused2, String name) {
+    public List<String> getHttpResponseHeader(Object unused, Void unused2, String name) {
       return Collections.emptyList();
     }
 
     @Override
-    public String getNetworkProtocolName(Void unused, @Nullable Void unused2) {
+    public String getNetworkProtocolName(Object unused, @Nullable Void unused2) {
       return "http";
     }
 
     @Override
-    public String getNetworkProtocolVersion(Void unused, @Nullable Void unused2) {
+    public String getNetworkProtocolVersion(Object unused, @Nullable Void unused2) {
       return "2.0";
     }
 
     @Nullable
     @Override
-    public String getServerAddress(Void request) {
+    public String getServerAddress(Object request) {
       return null;
     }
 
     @Nullable
     @Override
-    public Integer getServerPort(Void request) {
+    public Integer getServerPort(Object request) {
       return null;
     }
 
     @Override
     public InetSocketAddress getNetworkPeerInetSocketAddress(
-        Void request, @Nullable Void response) {
+        Object request, @Nullable Void response) {
       return PEER_ADDRESS;
     }
   }

instrumentation-api/src/main/java/io/opentelemetry/instrumentation/api/instrumenter/UnsafeAttributes.java

@@ -12,6 +12,7 @@
 import java.util.HashMap;
 import java.util.Map;
 import java.util.function.BiConsumer;
+import javax.annotation.Nullable;
 
 /**
  * The {@link AttributesBuilder} and {@link Attributes} used by the instrumentation API. We are able
@@ -29,6 +30,7 @@ final class UnsafeAttributes extends HashMap<AttributeKey<?>, Object>
 
   @SuppressWarnings("unchecked")
   @Override
+  @Nullable
   public <T> T get(AttributeKey<T> key) {
     return (T) super.get(key);
   }
@@ -62,7 +64,7 @@ public <T> AttributesBuilder put(AttributeKey<Long> key, int value) {
 
   @Override
   @CanIgnoreReturnValue
-  public <T> AttributesBuilder put(AttributeKey<T> key, T value) {
+  public <T> AttributesBuilder put(AttributeKey<T> key, @Nullable T value) {
     super.put(key, value);
     return this;
   }

instrumentation-api/src/main/java/io/opentelemetry/instrumentation/api/internal/ContextPropagationDebug.java

@@ -45,7 +45,7 @@ public final class ContextPropagationDebug {
   private final Context sourceContext;
   private final List<Propagation> locations;
   // context after adding debug locations
-  private Context wrappedContext;
+  @Nullable private Context wrappedContext;
 
   private ContextPropagationDebug(Context sourceContext) {
     this.sourceContext = sourceContext;

instrumentation-api/src/main/java/io/opentelemetry/instrumentation/api/internal/HttpProtocolUtil.java

@@ -13,13 +13,15 @@
  */
 public final class HttpProtocolUtil {
 
+  @Nullable
   public static String getProtocol(@Nullable String protocol) {
     if (protocol != null && protocol.startsWith("HTTP/")) {
       return "http";
     }
     return null;
   }
 
+  @Nullable
   public static String getVersion(@Nullable String protocol) {
     if (protocol != null && protocol.startsWith("HTTP/")) {
       return normalizeHttpVersion(protocol.substring("HTTP/".length()));

instrumentation-api/src/main/java/io/opentelemetry/instrumentation/api/internal/HttpRouteState.java

@@ -40,7 +40,10 @@ public static HttpRouteState create(
 
   // this method is used reflectively from InstrumentationApiContextBridging
   public static HttpRouteState create(
-      @Nullable String method, @Nullable String route, int updatedBySourceOrder, Span span) {
+      @Nullable String method,
+      @Nullable String route,
+      int updatedBySourceOrder,
+      @Nullable Span span) {
     return new HttpRouteState(method, route, updatedBySourceOrder, span);
   }
 
@@ -50,7 +53,10 @@ public static HttpRouteState create(
   @Nullable private volatile Span span;
 
   private HttpRouteState(
-      @Nullable String method, @Nullable String route, int updatedBySourceOrder, Span span) {
+      @Nullable String method,
+      @Nullable String route,
+      int updatedBySourceOrder,
+      @Nullable Span span) {
     this.method = method;
     this.updatedBySourceOrder = updatedBySourceOrder;
     this.route = route;

instrumentation-api/src/main/java/io/opentelemetry/instrumentation/api/internal/Initializer.java

@@ -0,0 +1,15 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.instrumentation.api.internal;
+
+/**
+ * See <a href="https://github.com/uber/NullAway/wiki/Supported-Annotations#initialization">NullAway
+ * spec</a>
+ *
+ * <p>This class is internal and is hence not for public use. Its APIs are unstable and can change
+ * at any time.
+ */
+public @interface Initializer {}

instrumentation-api/src/main/java/io/opentelemetry/instrumentation/api/internal/InstrumenterUtil.java

@@ -24,10 +24,12 @@ public final class InstrumenterUtil {
   private static InstrumenterAccess instrumenterAccess;
   private static InstrumenterBuilderAccess instrumenterBuilderAccess;
 
+  @Initializer
   public static void setInstrumenterAccess(InstrumenterAccess instrumenterAccess) {
     InstrumenterUtil.instrumenterAccess = instrumenterAccess;
   }
 
+  @Initializer
   public static void setInstrumenterBuilderAccess(
       InstrumenterBuilderAccess instrumenterBuilderAccess) {
     InstrumenterUtil.instrumenterBuilderAccess = instrumenterBuilderAccess;

instrumentation-api/src/main/java/io/opentelemetry/instrumentation/api/internal/cache/WeakLockFreeCache.java

@@ -7,6 +7,7 @@
 
 import io.opentelemetry.instrumentation.api.internal.cache.weaklockfree.WeakConcurrentMap;
 import java.util.function.Function;
+import javax.annotation.Nullable;
 
 final class WeakLockFreeCache<K, V> implements Cache<K, V> {
 
@@ -22,6 +23,7 @@ public V computeIfAbsent(K key, Function<? super K, ? extends V> mappingFunction
   }
 
   @Override
+  @Nullable
   public V get(K key) {
     return delegate.getIfPresent(key);
   }

instrumentation-api/src/main/java/io/opentelemetry/instrumentation/api/internal/cache/weaklockfree/AbstractWeakConcurrentMap.java

@@ -25,6 +25,8 @@
 
 package io.opentelemetry.instrumentation.api.internal.cache.weaklockfree;
 
+import static java.util.Objects.requireNonNull;
+
 import java.lang.ref.Reference;
 import java.lang.ref.ReferenceQueue;
 import java.lang.ref.WeakReference;
@@ -81,6 +83,7 @@ protected AbstractWeakConcurrentMap(ConcurrentMap<WeakKey<K>, V> target) {
    * @param key The key of the entry.
    * @return The value of the entry or the default value if it did not exist.
    */
+  @Nullable
   public V get(K key) {
     if (key == null) {
       throw new NullPointerException();
@@ -108,6 +111,7 @@ public V get(K key) {
    * @param key The key of the entry.
    * @return The value of the entry or null if it did not exist.
    */
+  @Nullable
   public V getIfPresent(K key) {
     if (key == null) {
       throw new NullPointerException();
@@ -225,6 +229,7 @@ public void clear() {
    * @return The default value for a key without value or {@code null} for not defining a default
    *     value.
    */
+  @Nullable
   protected V defaultValue(K key) {
     return null;
   }
@@ -328,7 +333,7 @@ public int hashCode() {
     }
 
     @Override
-    public boolean equals(@Nullable Object other) {
+    public boolean equals(Object other) {
       if (other instanceof WeakKey<?>) {
         return ((WeakKey<?>) other).get() == get();
       } else {
@@ -346,9 +351,9 @@ private class EntryIterator implements Iterator<Map.Entry<K, V>> {
 
     private final Iterator<Map.Entry<WeakKey<K>, V>> iterator;
 
-    private Map.Entry<WeakKey<K>, V> nextEntry;
+    @Nullable private Map.Entry<WeakKey<K>, V> nextEntry;
 
-    private K nextKey;
+    @Nullable private K nextKey;
 
     private EntryIterator(Iterator<Map.Entry<WeakKey<K>, V>> iterator) {
       this.iterator = iterator;
@@ -374,11 +379,12 @@ public boolean hasNext() {
 
     @Override
     public Map.Entry<K, V> next() {
-      if (nextKey == null) {
+      K key = nextKey;
+      if (key == null) {
         throw new NoSuchElementException();
       }
       try {
-        return new SimpleEntry(nextKey, nextEntry);
+        return new SimpleEntry(key, requireNonNull(nextEntry));
       } finally {
         findNext();
       }

instrumentation-api/src/main/java/io/opentelemetry/instrumentation/api/internal/cache/weaklockfree/WeakConcurrentMap.java

@@ -142,7 +142,7 @@ protected void resetLookupKey(LookupKey<K> lookupKey) {
   // can't use AutoClosable/try-with-resources as this project still supports Java 6
   static final class LookupKey<K> {
 
-    private K key;
+    @Nullable private K key;
     private int hashCode;
 
     @SuppressWarnings("OtelCanIgnoreReturnValueSuggester")
@@ -159,7 +159,7 @@ void reset() {
     }
 
     @Override
-    public boolean equals(@Nullable Object other) {
+    public boolean equals(Object other) {
       if (other instanceof WeakConcurrentMap.LookupKey<?>) {
         return ((LookupKey<?>) other).key == key;
       } else {
@@ -183,12 +183,14 @@ public int hashCode() {
   public static class WithInlinedExpunction<K, V> extends WeakConcurrentMap<K, V> {
 
     @Override
+    @Nullable
     public V get(K key) {
       expungeStaleEntries();
       return super.get(key);
     }
 
     @Override
+    @Nullable
     public V getIfPresent(K key) {
       expungeStaleEntries();
       return super.getIfPresent(key);

instrumentation-api/src/main/java/io/opentelemetry/instrumentation/api/internal/cache/weaklockfree/WeakConcurrentMapCleaner.java

@@ -5,12 +5,14 @@
 
 package io.opentelemetry.instrumentation.api.internal.cache.weaklockfree;
 
+import javax.annotation.Nullable;
+
 /**
  * This class is internal and is hence not for public use. Its APIs are unstable and can change at
  * any time.
  */
 public final class WeakConcurrentMapCleaner {
-  private static Thread thread;
+  @Nullable private static Thread thread;
 
   private WeakConcurrentMapCleaner() {}
 

instrumentation-api/src/main/java/io/opentelemetry/instrumentation/api/semconv/http/ForwardedUrlSchemeProvider.java

@@ -18,6 +18,7 @@ final class ForwardedUrlSchemeProvider<REQUEST> implements Function<REQUEST, Str
   }
 
   @Override
+  @Nullable
   public String apply(REQUEST request) {
     // try Forwarded
     for (String forwarded : getter.getHttpRequestHeader(request, "forwarded")) {