Fix error prone warnings

extras/src/main/java/com/google/gson/graph/GraphAdapterBuilder.java

@@ -31,10 +31,10 @@
 import com.google.gson.stream.JsonWriter;
 import java.io.IOException;
 import java.lang.reflect.Type;
+import java.util.ArrayDeque;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.IdentityHashMap;
-import java.util.LinkedList;
 import java.util.Map;
 import java.util.Queue;
 
@@ -79,6 +79,7 @@ public void registerOn(GsonBuilder gsonBuilder) {
 
   static class Factory implements TypeAdapterFactory, InstanceCreator<Object> {
     private final Map<Type, InstanceCreator<?>> instanceCreators;
+    @SuppressWarnings("ThreadLocalUsage")
     private final ThreadLocal<Graph> graphThreadLocal = new ThreadLocal<>();
 
     Factory(Map<Type, InstanceCreator<?>> instanceCreators) {
@@ -240,7 +241,7 @@ static class Graph {
      * The queue of elements to write during serialization. Unused during
      * deserialization.
      */
-    private final Queue<Element<?>> queue = new LinkedList<>();
+    private final Queue<Element<?>> queue = new ArrayDeque<>();
 
     /**
      * The instance currently being deserialized. Used as a backdoor between

extras/src/main/java/com/google/gson/interceptors/InterceptorFactory.java

@@ -46,7 +46,7 @@ static class InterceptorAdapter<T> extends TypeAdapter<T> {
     public InterceptorAdapter(TypeAdapter<T> delegate, Intercept intercept) {
       try {
         this.delegate = delegate;
-        this.postDeserializer = intercept.postDeserialize().newInstance();
+        this.postDeserializer = intercept.postDeserialize().getDeclaredConstructor().newInstance();
       } catch (Exception e) {
         throw new RuntimeException(e);
       }

gson/pom.xml

@@ -49,6 +49,12 @@
       <version>1.1.3</version>
       <scope>test</scope>
     </dependency>
+    <dependency>
+      <groupId>com.google.guava</groupId>
+      <artifactId>guava-testlib</artifactId>
+      <version>31.1-jre</version>
+      <scope>test</scope>
+    </dependency>
   </dependencies>
 
   <build>

gson/src/main/java/com/google/gson/Gson.java

@@ -166,6 +166,7 @@ public final class Gson {
    * with the type token provided to {@code getAdapter} as key and either
    * {@code FutureTypeAdapter} or a regular {@code TypeAdapter} as value.
    */
+  @SuppressWarnings("ThreadLocalUsage")
   private final ThreadLocal<Map<TypeToken<?>, TypeAdapter<?>>> threadLocalAdapterResults = new ThreadLocal<>();
 
   private final ConcurrentMap<TypeToken<?>, TypeAdapter<?>> typeTokenCache = new ConcurrentHashMap<>();

gson/src/main/java/com/google/gson/GsonBuilder.java

@@ -19,11 +19,11 @@
 import static com.google.gson.Gson.DEFAULT_COMPLEX_MAP_KEYS;
 import static com.google.gson.Gson.DEFAULT_DATE_PATTERN;
 import static com.google.gson.Gson.DEFAULT_ESCAPE_HTML;
+import static com.google.gson.Gson.DEFAULT_FORMATTING_STYLE;
 import static com.google.gson.Gson.DEFAULT_JSON_NON_EXECUTABLE;
 import static com.google.gson.Gson.DEFAULT_LENIENT;
 import static com.google.gson.Gson.DEFAULT_NUMBER_TO_NUMBER_STRATEGY;
 import static com.google.gson.Gson.DEFAULT_OBJECT_TO_NUMBER_STRATEGY;
-import static com.google.gson.Gson.DEFAULT_FORMATTING_STYLE;
 import static com.google.gson.Gson.DEFAULT_SERIALIZE_NULLS;
 import static com.google.gson.Gson.DEFAULT_SPECIALIZE_FLOAT_VALUES;
 import static com.google.gson.Gson.DEFAULT_USE_JDK_UNSAFE;
@@ -41,11 +41,11 @@
 import com.google.gson.stream.JsonWriter;
 import java.lang.reflect.Type;
 import java.text.DateFormat;
+import java.util.ArrayDeque;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.Date;
 import java.util.HashMap;
-import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
 import java.util.Objects;
@@ -104,7 +104,7 @@ public final class GsonBuilder {
   private boolean useJdkUnsafe = DEFAULT_USE_JDK_UNSAFE;
   private ToNumberStrategy objectToNumberStrategy = DEFAULT_OBJECT_TO_NUMBER_STRATEGY;
   private ToNumberStrategy numberToNumberStrategy = DEFAULT_NUMBER_TO_NUMBER_STRATEGY;
-  private final LinkedList<ReflectionAccessFilter> reflectionFilters = new LinkedList<>();
+  private final ArrayDeque<ReflectionAccessFilter> reflectionFilters = new ArrayDeque<>();
 
   /**
    * Creates a GsonBuilder instance that can be used to build Gson with various configuration

gson/src/main/java/com/google/gson/internal/ConstructorConstructor.java

@@ -342,8 +342,8 @@ private static <T> ObjectConstructor<T> newDefaultImplementationConstructor(
             return (T) new TreeMap<>();
           }
         };
-      } else if (type instanceof ParameterizedType && !(String.class.isAssignableFrom(
-          TypeToken.get(((ParameterizedType) type).getActualTypeArguments()[0]).getRawType()))) {
+      } else if (type instanceof ParameterizedType && !String.class.isAssignableFrom(
+          TypeToken.get(((ParameterizedType) type).getActualTypeArguments()[0]).getRawType())) {
         return new ObjectConstructor<T>() {
           @Override public T construct() {
             return (T) new LinkedHashMap<>();

gson/src/main/java/com/google/gson/internal/LazilyParsedNumber.java

@@ -98,7 +98,7 @@ public boolean equals(Object obj) {
     }
     if (obj instanceof LazilyParsedNumber) {
       LazilyParsedNumber other = (LazilyParsedNumber) obj;
-      return value == other.value || value.equals(other.value);
+      return value.equals(other.value);
     }
     return false;
   }

gson/src/main/java/com/google/gson/internal/LinkedTreeMap.java

@@ -304,6 +304,7 @@ Node<K, V> removeInternalByKey(Object key) {
     return node;
   }
 
+  @SuppressWarnings("ReferenceEquality")
   private void replaceInParent(Node<K, V> node, Node<K, V> replacement) {
     Node<K, V> parent = node.parent;
     node.parent = null;
@@ -315,7 +316,7 @@ private void replaceInParent(Node<K, V> node, Node<K, V> replacement) {
       if (parent.left == node) {
         parent.left = replacement;
       } else {
-        assert (parent.right == node);
+        assert parent.right == node;
         parent.right = replacement;
       }
     } else {
@@ -559,10 +560,13 @@ private abstract class LinkedTreeMapIterator<T> implements Iterator<T> {
     LinkedTreeMapIterator() {
     }
 
-    @Override public final boolean hasNext() {
+    @Override
+    @SuppressWarnings("ReferenceEquality")
+    public final boolean hasNext() {
       return next != header;
     }
 
+    @SuppressWarnings("ReferenceEquality")
     final Node<K, V> nextNode() {
       Node<K, V> e = next;
       if (e == header) {

gson/src/main/java/com/google/gson/internal/bind/ArrayTypeAdapter.java

@@ -37,7 +37,7 @@ public final class ArrayTypeAdapter<E> extends TypeAdapter<Object> {
   public static final TypeAdapterFactory FACTORY = new TypeAdapterFactory() {
     @Override public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> typeToken) {
       Type type = typeToken.getType();
-      if (!(type instanceof GenericArrayType || type instanceof Class && ((Class<?>) type).isArray())) {
+      if (!(type instanceof GenericArrayType || (type instanceof Class && ((Class<?>) type).isArray()))) {
         return null;
       }
 

gson/src/main/java/com/google/gson/internal/bind/TreeTypeAdapter.java

@@ -158,7 +158,7 @@ private static final class SingleTypeFactory implements TypeAdapterFactory {
     @Override
     public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> type) {
       boolean matches = exactType != null
-          ? exactType.equals(type) || matchRawType && exactType.getType() == type.getRawType()
+          ? exactType.equals(type) || (matchRawType && exactType.getType() == type.getRawType())
           : hierarchyType.isAssignableFrom(type.getRawType());
       return matches
           ? new TreeTypeAdapter<>((JsonSerializer<T>) serializer,

gson/src/main/java/com/google/gson/internal/bind/TypeAdapters.java

@@ -123,7 +123,7 @@ public Class read(JsonReader in) throws IOException {
     @Override public void write(JsonWriter out, BitSet src) throws IOException {
       out.beginArray();
       for (int i = 0, length = src.length(); i < length; i++) {
-        int value = (src.get(i)) ? 1 : 0;
+        int value = src.get(i) ? 1 : 0;
         out.value(value);
       }
       out.endArray();
@@ -883,7 +883,7 @@ public EnumTypeAdapter(final Class<T> classOfT) {
         });
         for (Field constantField : constantFields) {
           @SuppressWarnings("unchecked")
-          T constant = (T)(constantField.get(null));
+          T constant = (T) constantField.get(null);
           String name = constant.name();
           String toStringVal = constant.toString();
 

gson/src/main/java/com/google/gson/stream/JsonWriter.java

@@ -637,7 +637,7 @@ public JsonWriter value(Number value) throws IOException {
     out.close();
 
     int size = stackSize;
-    if (size > 1 || size == 1 && stack[size - 1] != NONEMPTY_DOCUMENT) {
+    if (size > 1 || (size == 1 && stack[size - 1] != NONEMPTY_DOCUMENT)) {
       throw new IOException("Incomplete document");
     }
     stackSize = 0;

gson/src/test/java/com/google/gson/JsonArrayTest.java

@@ -20,6 +20,7 @@
 import static com.google.common.truth.Truth.assertWithMessage;
 import static org.junit.Assert.fail;
 
+import com.google.common.testing.EqualsTester;
 import com.google.gson.common.MoreAsserts;
 import java.math.BigInteger;
 import org.junit.Test;
@@ -35,12 +36,11 @@ public void testEqualsOnEmptyArray() {
   }
 
   @Test
-  @SuppressWarnings("TruthSelfEquals")
   public void testEqualsNonEmptyArray() {
     JsonArray a = new JsonArray();
     JsonArray b = new JsonArray();
 
-    assertThat(a).isEqualTo(a);
+    new EqualsTester().addEqualityGroup(a).testEquals();
 
     a.add(new JsonObject());
     assertThat(a.equals(b)).isFalse();

gson/src/test/java/com/google/gson/JsonObjectTest.java

@@ -19,6 +19,7 @@
 import static com.google.common.truth.Truth.assertThat;
 import static org.junit.Assert.fail;
 
+import com.google.common.testing.EqualsTester;
 import com.google.gson.common.MoreAsserts;
 import java.util.AbstractMap.SimpleEntry;
 import java.util.ArrayDeque;
@@ -163,12 +164,11 @@ public void testEqualsOnEmptyObject() {
   }
 
   @Test
-  @SuppressWarnings("TruthSelfEquals")
   public void testEqualsNonEmptyObject() {
     JsonObject a = new JsonObject();
     JsonObject b = new JsonObject();
 
-    assertThat(a).isEqualTo(a);
+    new EqualsTester().addEqualityGroup(a).testEquals();
 
     a.add("foo", new JsonObject());
     assertThat(a.equals(b)).isFalse();

pom.xml

@@ -98,7 +98,7 @@
             <compilerArgs>
               <!-- Args related to Error Prone, see: https://errorprone.info/docs/installation#maven -->
               <arg>-XDcompilePolicy=simple</arg>
-              <arg>-Xplugin:ErrorProne</arg>
+              <arg>-Xplugin:ErrorProne -XepExcludedPaths:.*gson/src/test.*|.*extras/src/test.*|.*proto.*</arg>
               <arg>-J--add-exports=jdk.compiler/com.sun.tools.javac.api=ALL-UNNAMED</arg>
               <arg>-J--add-exports=jdk.compiler/com.sun.tools.javac.file=ALL-UNNAMED</arg>
               <arg>-J--add-exports=jdk.compiler/com.sun.tools.javac.main=ALL-UNNAMED</arg>