From dc20b7561af3a793e4945842040e956803b641c9 Mon Sep 17 00:00:00 2001
From: Maicol <79454487+MaicolAntali@users.noreply.github.com>
Date: Wed, 1 Mar 2023 23:23:27 +0100
Subject: [PATCH] Fix error prone warns (#2320)

* Adds `@SuppressWarnings("NarrowingCompoundAssignment")`

* Adds `@SuppressWarnings("TypeParameterUnusedInFormals")`

* Adds `@SuppressWarnings("JavaUtilDate")`

* Adds a limit to `String.split()`

* Add `error_prone_annotations` to the `pom.xml`

* Adds `@InlineMe(...)` to deprecated methods

* Adds `@SuppressWarnings("ImmutableEnumChecker")`

* Adds `@SuppressWarnings("ModifiedButNotUsed")`

* Adds `@SuppressWarnings("MixedMutabilityReturnType")`

* Removes an unused import

* Adds `requires` to `module-info.java`

* Adds ErrorProne `link` into `pom.xml`

* Remove unused imports

Removed from:
- ParseBenchmark

* Adds `@SuppressWarnings("EqualsGetClass")`

* Excludes from `proto` just the generated code.

Replaces `.*proto.*` with `.*/generated-test-sources/protobuf/.*` in such way will be excluded just the generated code and not the whole `proto` directory

* Removes an unused variable

Removes the `descriptor` variable because is unused.

* Fixes the `BadImport` warn into `ProtosWithAnnotationsTest`

* Fixes the `BadImport` warns into `ProtosWithAnnotationsTest`

* Enables ErrorProne in `gson/src/test.*`

Removes the `gson/src/test.*` path from the `-XepExcludedPaths` parameter of the ErrorProne plugin

* Fixes `UnusedVariable` warns

This commit fix all `UnusedVariable` warns given by ErrorProne in the `gson/src/test.*` path.

Some field is annotated with `@Keep` that means is used by reflection.
In some other case the record is annotated with `@SuppressWarnings("unused")`

* Fixes `JavaUtilDate` warns

This commit fix all `JavaUtilDate` warns given by ErrorProne in the `gson/src/test.*` path.

Classes/Methods are annotated with `@SuppressWarnings("JavaUtilDate")` because it's not possible use differente Date API.

* Fixes `EqualsGetClass` warns

This commit fix all `EqualsGetClass` warns given by ErrorProne in the `gson/src/test.*` path.

I have rewrite the `equals()` methods to use `instanceof`

* Replaces pattern matching for instanceof with casts

* Fixes `JdkObsolete` warns

This commit fix all `JdkObsolete` warns given by ErrorProne in the `gson/src/test.*` path.

In some cases I have replaced the obsolete JDK classes with the newest alternatives.  In other cases, I have added the `@SuppressWarnings("JdkObsolete")`

* Fixes `ClassCanBeStatic` warns

This commit fix all `ClassCanBeStatic` warns given by ErrorProne in the `gson/src/test.*` path.

I have added the `static` keyword, or I have added `@SuppressWarnings("ClassCanBeStatic")`

* Fixes `UndefinedEquals` warns

This commit fix all `UndefinedEquals` warns given by ErrorProne in the `gson/src/test.*` path.

I have added `@SuppressWarnings("UndefinedEquals")` or fixed the asserts

Note: In this commit I have also renamed a test from `testRawCollectionDeserializationNotAlllowed` to `testRawCollectionDeserializationNotAllowed`

* Fixes `GetClassOnEnum` warns

This commit fix all `GetClassOnEnum` warns given by ErrorProne in the `gson/src/test.*` path.

I have replaced the `.getClass()` with `.getDeclaringClass()`

* Fixes `ImmutableEnumChecker` warns

This commit fix all `ImmutableEnumChecker` warns given by ErrorProne in the `gson/src/test.*` path.

I have added the `final` keyword, or I have added the `@SuppressWarnings("ImmutableEnumChecker")` annotation

* Fixes `StaticAssignmentOfThrowable` warns

This commit fix all `StaticAssignmentOfThrowable` warns given by ErrorProne in the `gson/src/test.*` path.

* Fixes `AssertionFailureIgnored` warns

This commit fix all `AssertionFailureIgnored` warns given by ErrorProne in the `gson/src/test.*` path.

I have added the `@SuppressWarnings("AssertionFailureIgnored")` annotation

* Fixes `ModifiedButNotUsed` warns

This commit fix all `ModifiedButNotUsed` warns given by ErrorProne in the `gson/src/test.*` path.

I have added the `@SuppressWarnings("ModifiedButNotUsed")` annotation

* Fixes `MissingSummary` warns

This commit fix all `MissingSummary` warns given by ErrorProne in the `gson/src/test.*` path.

I have remove the Javadoc `@author`

* Fixes `FloatingPointLiteralPrecision` warns

This commit fix all `FloatingPointLiteralPrecision` warns given by ErrorProne in the `gson/src/test.*` path.

I have added the `@SuppressWarnings("FloatingPointLiteralPrecision")` annotation

* Fixes `StringSplitter` warns

This commit fix all `StringSplitter` warns given by ErrorProne in the `gson/src/test.*` path.

I have replaced the `String.split(...)` with `Splitter`

* Fixes `EmptyCatch` warns

This commit fix all `EmptyCatch` warns given by ErrorProne in the `gson/src/test.*` path.

* Fixes `UnicodeEscape` warns

This commit fix all `UnicodeEscape` warns given by ErrorProne in the `gson/src/test.*` path.

* Fixes `EmptyBlockTag` warns

This commit fix all `EmptyBlockTag` warns given by ErrorProne in the `gson/src/test.*` path.

* Fixes `LongFloatConversion` warns

This commit fix all `LongFloatConversion` warns given by ErrorProne in the `gson/src/test.*` path.

* Fixes `LongDoubleConversion` warns

This commit fix all `LongDoubleConversion` warns given by ErrorProne in the `gson/src/test.*` path.

* Fixes `TruthAssertExpected` warns

This commit fix all `TruthAssertExpected` warns given by ErrorProne in the `gson/src/test.*` path.

* Fixes `UnusedMethod` warns

This commit fix all `UnusedMethod` warns given by ErrorProne in the `gson/src/test.*` path.

* Fixes `UnusedTypeParameter` warns

This commit fix all `UnusedTypeParameter` warns given by ErrorProne in the `gson/src/test.*` path.

* Fixes `CatchFail` warns

This commit fix all `CatchFail` warns given by ErrorProne in the `gson/src/test.*` path.

* Fixes `MathAbsoluteNegative` warns

This commit fix all `MathAbsoluteNegative` warns given by ErrorProne in the `gson/src/test.*` path.

* Fixes `LoopOverCharArray` warns

This commit fix all `LoopOverCharArray` warns given by ErrorProne in the `gson/src/test.*` path.

`toCharArray` allocates a new array, using `charAt` is more efficient

* Fixes `HidingField` warns

This commit fix all `HidingField` warns given by ErrorProne in the `gson/src/test.*` path.

* Implements code review feedback

* Implements code review feedback

This commit implements some other code review feedback

* Enable ErrorProne in `extra`

Thi commit removes the `.*extras/src/test.*` path from the `-XepExcludedPaths` parameter of ErrorProne.

* Fix the `JavaUtilDate` warns

This commit fix all `JavaUtilDate` warns given by ErrorProne in the `extras/src/test.*` path.

* Implements code review feedback

* Removes redundant new-line

* Implements code review feedback

* Adds `JDK11` to run test with `--release 11`

* Revert "Adds `JDK11` to run test with `--release 11`"

This reverts commit a7cca386098ae847a10a31c09c3ab9b11eee5920.
---
 .../typeadapters/UtcDateTypeAdapterTest.java  |  1 +
 gson/pom.xml                                  |  6 ++
 gson/src/main/java/com/google/gson/Gson.java  |  8 +--
 .../gson/JsonDeserializationContext.java      |  1 +
 .../main/java/com/google/gson/JsonParser.java |  4 ++
 .../com/google/gson/internal/JavaVersion.java |  2 +-
 .../bind/ReflectiveTypeAdapterFactory.java    |  1 +
 .../gson/internal/bind/TreeTypeAdapter.java   |  5 +-
 .../gson/internal/sql/SqlDateTypeAdapter.java |  1 +
 .../gson/internal/sql/SqlTimeTypeAdapter.java |  1 +
 .../internal/sql/SqlTimestampTypeAdapter.java |  1 +
 .../gson/internal/sql/SqlTypesSupport.java    |  1 +
 .../com/google/gson/stream/JsonReader.java    |  4 +-
 gson/src/main/java/module-info.java           |  3 +
 .../java/com/google/gson/CommentsTest.java    |  2 +
 .../gson/InnerClassExclusionStrategyTest.java |  1 +
 .../java/com/google/gson/JsonArrayTest.java   |  2 +
 .../java/com/google/gson/JsonNullTest.java    |  2 +
 .../google/gson/ObjectTypeAdapterTest.java    |  2 +-
 .../gson/OverrideCoreTypeAdaptersTest.java    |  2 +
 .../gson/ParameterizedTypeFixtures.java       | 22 ++------
 .../gson/VersionExclusionStrategyTest.java    |  4 ++
 .../com/google/gson/common/TestTypes.java     | 31 ++++------
 .../gson/functional/CollectionTest.java       | 10 ++--
 .../functional/CustomDeserializerTest.java    |  1 +
 .../functional/CustomTypeAdaptersTest.java    | 10 +++-
 .../functional/DefaultTypeAdaptersTest.java   |  2 +
 .../functional/DelegateTypeAdapterTest.java   |  4 +-
 .../com/google/gson/functional/EnumTest.java  | 11 ++--
 .../google/gson/functional/EscapingTest.java  |  2 +-
 .../gson/functional/ExposeFieldsTest.java     | 12 +++-
 .../gson/functional/FieldExclusionTest.java   |  2 +
 .../GsonVersionDiagnosticsTest.java           | 23 +++-----
 .../gson/functional/InheritanceTest.java      |  1 +
 .../gson/functional/Java17RecordTest.java     |  6 ++
 .../JsonAdapterAnnotationOnClassesTest.java   |  6 +-
 ...JsonAdapterSerializerDeserializerTest.java | 21 +++++--
 .../google/gson/functional/ObjectTest.java    |  6 +-
 .../functional/ParameterizedTypesTest.java    | 56 ++++---------------
 .../gson/functional/PrettyPrintingTest.java   |  3 +-
 .../google/gson/functional/PrimitiveTest.java |  4 +-
 .../gson/functional/PrintFormattingTest.java  |  1 +
 .../gson/functional/ReflectionAccessTest.java |  2 +-
 .../functional/StreamingTypeAdaptersTest.java |  5 +-
 .../google/gson/functional/StringTest.java    |  2 +-
 .../ToNumberPolicyFunctionalTest.java         |  9 +--
 .../gson/functional/TreeTypeAdaptersTest.java |  1 +
 .../gson/internal/LinkedTreeMapTest.java      |  6 +-
 .../UnsafeAllocatorInstantiationTest.java     | 26 ++++-----
 .../bind/DefaultDateTypeAdapterTest.java      |  2 +
 .../internal/bind/util/ISO8601UtilsTest.java  |  5 ++
 .../google/gson/reflect/TypeTokenTest.java    |  2 +
 .../com/google/gson/regression/OSGiTest.java  |  3 +-
 .../google/gson/stream/JsonReaderTest.java    | 13 +++--
 .../google/gson/metrics/BagOfPrimitives.java  | 25 +++++----
 .../CollectionsDeserializationBenchmark.java  |  2 +
 .../google/gson/metrics/ParseBenchmark.java   |  3 +-
 pom.xml                                       |  3 +-
 .../functional/ProtosWithAnnotationsTest.java | 20 +++----
 .../ProtosWithPrimitiveTypesTest.java         |  1 -
 60 files changed, 225 insertions(+), 193 deletions(-)

diff --git a/extras/src/test/java/com/google/gson/typeadapters/UtcDateTypeAdapterTest.java b/extras/src/test/java/com/google/gson/typeadapters/UtcDateTypeAdapterTest.java
index b5201835..3d3262a3 100644
--- a/extras/src/test/java/com/google/gson/typeadapters/UtcDateTypeAdapterTest.java
+++ b/extras/src/test/java/com/google/gson/typeadapters/UtcDateTypeAdapterTest.java
@@ -29,6 +29,7 @@ import java.util.Locale;
 import java.util.TimeZone;
 import org.junit.Test;
 
+@SuppressWarnings("JavaUtilDate")
 public final class UtcDateTypeAdapterTest {
   private final Gson gson = new GsonBuilder()
     .registerTypeAdapter(Date.class, new UtcDateTypeAdapter())
diff --git a/gson/pom.xml b/gson/pom.xml
index deed98dd..d80226c0 100644
--- a/gson/pom.xml
+++ b/gson/pom.xml
@@ -55,6 +55,12 @@
       <version>31.1-jre</version>
       <scope>test</scope>
     </dependency>
+    <dependency>
+      <groupId>com.google.errorprone</groupId>
+      <artifactId>error_prone_annotations</artifactId>
+      <version>2.18.0</version>
+      <optional>true</optional>
+    </dependency>
   </dependencies>
 
   <build>
diff --git a/gson/src/main/java/com/google/gson/Gson.java b/gson/src/main/java/com/google/gson/Gson.java
index 054b1f92..45336a87 100644
--- a/gson/src/main/java/com/google/gson/Gson.java
+++ b/gson/src/main/java/com/google/gson/Gson.java
@@ -1011,7 +1011,7 @@ public final class Gson {
    * @see #fromJson(String, Class)
    * @see #fromJson(String, TypeToken)
    */
-  @SuppressWarnings("unchecked")
+  @SuppressWarnings({"unchecked", "TypeParameterUnusedInFormals"})
   public <T> T fromJson(String json, Type typeOfT) throws JsonSyntaxException {
     return (T) fromJson(json, TypeToken.get(typeOfT));
   }
@@ -1104,7 +1104,7 @@ public final class Gson {
    * @see #fromJson(Reader, Class)
    * @see #fromJson(Reader, TypeToken)
    */
-  @SuppressWarnings("unchecked")
+  @SuppressWarnings({"unchecked", "TypeParameterUnusedInFormals"})
   public <T> T fromJson(Reader json, Type typeOfT) throws JsonIOException, JsonSyntaxException {
     return (T) fromJson(json, TypeToken.get(typeOfT));
   }
@@ -1183,7 +1183,7 @@ public final class Gson {
    * @see #fromJson(Reader, Type)
    * @see #fromJson(JsonReader, TypeToken)
    */
-  @SuppressWarnings("unchecked")
+  @SuppressWarnings({"unchecked", "TypeParameterUnusedInFormals"})
   public <T> T fromJson(JsonReader reader, Type typeOfT) throws JsonIOException, JsonSyntaxException {
     return (T) fromJson(reader, TypeToken.get(typeOfT));
   }
@@ -1297,7 +1297,7 @@ public final class Gson {
    * @see #fromJson(JsonElement, Class)
    * @see #fromJson(JsonElement, TypeToken)
    */
-  @SuppressWarnings("unchecked")
+  @SuppressWarnings({"unchecked", "TypeParameterUnusedInFormals"})
   public <T> T fromJson(JsonElement json, Type typeOfT) throws JsonSyntaxException {
     return (T) fromJson(json, TypeToken.get(typeOfT));
   }
diff --git a/gson/src/main/java/com/google/gson/JsonDeserializationContext.java b/gson/src/main/java/com/google/gson/JsonDeserializationContext.java
index 00c75054..093653d9 100644
--- a/gson/src/main/java/com/google/gson/JsonDeserializationContext.java
+++ b/gson/src/main/java/com/google/gson/JsonDeserializationContext.java
@@ -40,5 +40,6 @@ public interface JsonDeserializationContext {
    * @return An object of type typeOfT.
    * @throws JsonParseException if the parse tree does not contain expected data.
    */
+  @SuppressWarnings("TypeParameterUnusedInFormals")
   public <T> T deserialize(JsonElement json, Type typeOfT) throws JsonParseException;
 }
\ No newline at end of file
diff --git a/gson/src/main/java/com/google/gson/JsonParser.java b/gson/src/main/java/com/google/gson/JsonParser.java
index 5b800420..20d3750c 100644
--- a/gson/src/main/java/com/google/gson/JsonParser.java
+++ b/gson/src/main/java/com/google/gson/JsonParser.java
@@ -15,6 +15,7 @@
  */
 package com.google.gson;
 
+import com.google.errorprone.annotations.InlineMe;
 import com.google.gson.internal.Streams;
 import com.google.gson.stream.JsonReader;
 import com.google.gson.stream.JsonToken;
@@ -111,18 +112,21 @@ public final class JsonParser {
 
   /** @deprecated Use {@link JsonParser#parseString} */
   @Deprecated
+  @InlineMe(replacement = "JsonParser.parseString(json)", imports = "com.google.gson.JsonParser")
   public JsonElement parse(String json) throws JsonSyntaxException {
     return parseString(json);
   }
 
   /** @deprecated Use {@link JsonParser#parseReader(Reader)} */
   @Deprecated
+  @InlineMe(replacement = "JsonParser.parseReader(json)", imports = "com.google.gson.JsonParser")
   public JsonElement parse(Reader json) throws JsonIOException, JsonSyntaxException {
     return parseReader(json);
   }
 
   /** @deprecated Use {@link JsonParser#parseReader(JsonReader)} */
   @Deprecated
+  @InlineMe(replacement = "JsonParser.parseReader(json)", imports = "com.google.gson.JsonParser")
   public JsonElement parse(JsonReader json) throws JsonIOException, JsonSyntaxException {
     return parseReader(json);
   }
diff --git a/gson/src/main/java/com/google/gson/internal/JavaVersion.java b/gson/src/main/java/com/google/gson/internal/JavaVersion.java
index df8e9a49..21130ff9 100644
--- a/gson/src/main/java/com/google/gson/internal/JavaVersion.java
+++ b/gson/src/main/java/com/google/gson/internal/JavaVersion.java
@@ -45,7 +45,7 @@ public final class JavaVersion {
   // Parses both legacy 1.8 style and newer 9.0.4 style 
   private static int parseDotted(String javaVersion) {
     try {
-      String[] parts = javaVersion.split("[._]");
+      String[] parts = javaVersion.split("[._]", 3);
       int firstVer = Integer.parseInt(parts[0]);
       if (firstVer == 1 && parts.length > 1) {
         return Integer.parseInt(parts[1]);
diff --git a/gson/src/main/java/com/google/gson/internal/bind/ReflectiveTypeAdapterFactory.java b/gson/src/main/java/com/google/gson/internal/bind/ReflectiveTypeAdapterFactory.java
index 07fee7df..9194fc33 100644
--- a/gson/src/main/java/com/google/gson/internal/bind/ReflectiveTypeAdapterFactory.java
+++ b/gson/src/main/java/com/google/gson/internal/bind/ReflectiveTypeAdapterFactory.java
@@ -81,6 +81,7 @@ public final class ReflectiveTypeAdapterFactory implements TypeAdapterFactory {
   }
 
   /** first element holds the default name */
+  @SuppressWarnings("MixedMutabilityReturnType")
   private List<String> getFieldNames(Field f) {
     SerializedName annotation = f.getAnnotation(SerializedName.class);
     if (annotation == null) {
diff --git a/gson/src/main/java/com/google/gson/internal/bind/TreeTypeAdapter.java b/gson/src/main/java/com/google/gson/internal/bind/TreeTypeAdapter.java
index 47ca8fc0..a1a5f760 100644
--- a/gson/src/main/java/com/google/gson/internal/bind/TreeTypeAdapter.java
+++ b/gson/src/main/java/com/google/gson/internal/bind/TreeTypeAdapter.java
@@ -174,8 +174,9 @@ public final class TreeTypeAdapter<T> extends SerializationDelegatingTypeAdapter
     @Override public JsonElement serialize(Object src, Type typeOfSrc) {
       return gson.toJsonTree(src, typeOfSrc);
     }
-    @SuppressWarnings("unchecked")
-    @Override public <R> R deserialize(JsonElement json, Type typeOfT) throws JsonParseException {
+    @Override
+    @SuppressWarnings({"unchecked", "TypeParameterUnusedInFormals"})
+    public <R> R deserialize(JsonElement json, Type typeOfT) throws JsonParseException {
       return gson.fromJson(json, typeOfT);
     }
   }
diff --git a/gson/src/main/java/com/google/gson/internal/sql/SqlDateTypeAdapter.java b/gson/src/main/java/com/google/gson/internal/sql/SqlDateTypeAdapter.java
index 6ae4c3ef..271f23c2 100644
--- a/gson/src/main/java/com/google/gson/internal/sql/SqlDateTypeAdapter.java
+++ b/gson/src/main/java/com/google/gson/internal/sql/SqlDateTypeAdapter.java
@@ -36,6 +36,7 @@ import java.util.Date;
  * this class state. DateFormat isn't thread safe either, so this class has
  * to synchronize its read and write methods.
  */
+@SuppressWarnings("JavaUtilDate")
 final class SqlDateTypeAdapter extends TypeAdapter<java.sql.Date> {
   static final TypeAdapterFactory FACTORY = new TypeAdapterFactory() {
     @SuppressWarnings("unchecked") // we use a runtime check to make sure the 'T's equal
diff --git a/gson/src/main/java/com/google/gson/internal/sql/SqlTimeTypeAdapter.java b/gson/src/main/java/com/google/gson/internal/sql/SqlTimeTypeAdapter.java
index c2a37073..ac327ff1 100644
--- a/gson/src/main/java/com/google/gson/internal/sql/SqlTimeTypeAdapter.java
+++ b/gson/src/main/java/com/google/gson/internal/sql/SqlTimeTypeAdapter.java
@@ -37,6 +37,7 @@ import java.util.Date;
  * this class state. DateFormat isn't thread safe either, so this class has
  * to synchronize its read and write methods.
  */
+@SuppressWarnings("JavaUtilDate")
 final class SqlTimeTypeAdapter extends TypeAdapter<Time> {
   static final TypeAdapterFactory FACTORY = new TypeAdapterFactory() {
     @SuppressWarnings("unchecked") // we use a runtime check to make sure the 'T's equal
diff --git a/gson/src/main/java/com/google/gson/internal/sql/SqlTimestampTypeAdapter.java b/gson/src/main/java/com/google/gson/internal/sql/SqlTimestampTypeAdapter.java
index 5c77f839..0ca44c1b 100644
--- a/gson/src/main/java/com/google/gson/internal/sql/SqlTimestampTypeAdapter.java
+++ b/gson/src/main/java/com/google/gson/internal/sql/SqlTimestampTypeAdapter.java
@@ -27,6 +27,7 @@ import java.io.IOException;
 import java.sql.Timestamp;
 import java.util.Date;
 
+@SuppressWarnings("JavaUtilDate")
 class SqlTimestampTypeAdapter extends TypeAdapter<Timestamp> {
   static final TypeAdapterFactory FACTORY = new TypeAdapterFactory() {
     @SuppressWarnings("unchecked") // we use a runtime check to make sure the 'T's equal
diff --git a/gson/src/main/java/com/google/gson/internal/sql/SqlTypesSupport.java b/gson/src/main/java/com/google/gson/internal/sql/SqlTypesSupport.java
index b82ace74..e5f7bb1d 100644
--- a/gson/src/main/java/com/google/gson/internal/sql/SqlTypesSupport.java
+++ b/gson/src/main/java/com/google/gson/internal/sql/SqlTypesSupport.java
@@ -33,6 +33,7 @@ import com.google.gson.internal.bind.DefaultDateTypeAdapter.DateType;
  * it is {@code false} all other constants will be {@code null} and
  * there will be no support for {@code java.sql} types.
  */
+@SuppressWarnings("JavaUtilDate")
 public final class SqlTypesSupport {
   /**
    * {@code true} if {@code java.sql} types are supported,
diff --git a/gson/src/main/java/com/google/gson/stream/JsonReader.java b/gson/src/main/java/com/google/gson/stream/JsonReader.java
index 718a7c2a..559ab2db 100644
--- a/gson/src/main/java/com/google/gson/stream/JsonReader.java
+++ b/gson/src/main/java/com/google/gson/stream/JsonReader.java
@@ -1603,7 +1603,7 @@ public class JsonReader implements Closeable {
         throw syntaxError("Unterminated escape sequence");
       }
       // Equivalent to Integer.parseInt(stringPool.get(buffer, pos, 4), 16);
-      char result = 0;
+      int result = 0;
       for (int i = pos, end = i + 4; i < end; i++) {
         char c = buffer[i];
         result <<= 4;
@@ -1618,7 +1618,7 @@ public class JsonReader implements Closeable {
         }
       }
       pos += 4;
-      return result;
+      return (char) result;
 
     case 't':
       return '\t';
diff --git a/gson/src/main/java/module-info.java b/gson/src/main/java/module-info.java
index 410569bc..a7b6afbb 100644
--- a/gson/src/main/java/module-info.java
+++ b/gson/src/main/java/module-info.java
@@ -24,6 +24,9 @@ module com.google.gson {
   exports com.google.gson.reflect;
   exports com.google.gson.stream;
 
+  // Dependency on Error Prone Annotations
+  requires static com.google.errorprone.annotations;
+
   // Optional dependency on java.sql
   requires static java.sql;
 
diff --git a/gson/src/test/java/com/google/gson/CommentsTest.java b/gson/src/test/java/com/google/gson/CommentsTest.java
index f1bcd948..a83520db 100644
--- a/gson/src/test/java/com/google/gson/CommentsTest.java
+++ b/gson/src/test/java/com/google/gson/CommentsTest.java
@@ -23,6 +23,8 @@ import java.util.List;
 import org.junit.Test;
 
 /**
+ * Tests that by default Gson accepts several forms of comments.
+ *
  * @author Jesse Wilson
  */
 public final class CommentsTest {
diff --git a/gson/src/test/java/com/google/gson/InnerClassExclusionStrategyTest.java b/gson/src/test/java/com/google/gson/InnerClassExclusionStrategyTest.java
index 67ad9b29..1059f779 100644
--- a/gson/src/test/java/com/google/gson/InnerClassExclusionStrategyTest.java
+++ b/gson/src/test/java/com/google/gson/InnerClassExclusionStrategyTest.java
@@ -56,6 +56,7 @@ public class InnerClassExclusionStrategyTest {
     assertThat(excluder.excludeField(f, true)).isFalse();
   }
 
+  @SuppressWarnings("ClassCanBeStatic")
   class InnerClass {
   }
 
diff --git a/gson/src/test/java/com/google/gson/JsonArrayTest.java b/gson/src/test/java/com/google/gson/JsonArrayTest.java
index bd0f7a17..c3c0184f 100644
--- a/gson/src/test/java/com/google/gson/JsonArrayTest.java
+++ b/gson/src/test/java/com/google/gson/JsonArrayTest.java
@@ -26,6 +26,8 @@ import java.math.BigInteger;
 import org.junit.Test;
 
 /**
+ * Tests handling of JSON arrays.
+ *
  * @author Jesse Wilson
  */
 public final class JsonArrayTest {
diff --git a/gson/src/test/java/com/google/gson/JsonNullTest.java b/gson/src/test/java/com/google/gson/JsonNullTest.java
index caaf0ad8..ca995b92 100644
--- a/gson/src/test/java/com/google/gson/JsonNullTest.java
+++ b/gson/src/test/java/com/google/gson/JsonNullTest.java
@@ -22,6 +22,8 @@ import com.google.gson.common.MoreAsserts;
 import org.junit.Test;
 
 /**
+ * Tests handling of JSON nulls.
+ *
  * @author Jesse Wilson
  */
 public final class JsonNullTest {
diff --git a/gson/src/test/java/com/google/gson/ObjectTypeAdapterTest.java b/gson/src/test/java/com/google/gson/ObjectTypeAdapterTest.java
index cdfdb013..274de8fa 100644
--- a/gson/src/test/java/com/google/gson/ObjectTypeAdapterTest.java
+++ b/gson/src/test/java/com/google/gson/ObjectTypeAdapterTest.java
@@ -111,7 +111,7 @@ public final class ObjectTypeAdapterTest {
     assertThat(actualTimes).isEqualTo(times);
   }
 
-  @SuppressWarnings("unused")
+  @SuppressWarnings({"unused", "ClassCanBeStatic"})
   private class RuntimeType {
     Object a = 5;
     Object b = Arrays.asList(1, 2, null);
diff --git a/gson/src/test/java/com/google/gson/OverrideCoreTypeAdaptersTest.java b/gson/src/test/java/com/google/gson/OverrideCoreTypeAdaptersTest.java
index fab0d96b..781989f4 100644
--- a/gson/src/test/java/com/google/gson/OverrideCoreTypeAdaptersTest.java
+++ b/gson/src/test/java/com/google/gson/OverrideCoreTypeAdaptersTest.java
@@ -25,6 +25,8 @@ import java.util.Locale;
 import org.junit.Test;
 
 /**
+ * Tests handling of Core Type Adapters
+ *
  * @author Jesse Wilson
  */
 public class OverrideCoreTypeAdaptersTest {
diff --git a/gson/src/test/java/com/google/gson/ParameterizedTypeFixtures.java b/gson/src/test/java/com/google/gson/ParameterizedTypeFixtures.java
index 3aca9fb7..b3fce37c 100644
--- a/gson/src/test/java/com/google/gson/ParameterizedTypeFixtures.java
+++ b/gson/src/test/java/com/google/gson/ParameterizedTypeFixtures.java
@@ -16,6 +16,7 @@
 
 package com.google.gson;
 
+import com.google.common.base.Objects;
 import com.google.gson.internal.$Gson$Types;
 
 import com.google.gson.internal.Primitives;
@@ -35,7 +36,7 @@ import java.lang.reflect.Type;
  */
 public class ParameterizedTypeFixtures {
 
-  public static class MyParameterizedType<T> {
+  public static final class MyParameterizedType<T> {
     public final T value;
     public MyParameterizedType(T value) {
       this.value = value;
@@ -80,27 +81,16 @@ public class ParameterizedTypeFixtures {
       return value == null ? 0 : value.hashCode();
     }
 
-    @SuppressWarnings("unchecked")
     @Override
     public boolean equals(Object obj) {
       if (this == obj) {
         return true;
       }
-      if (obj == null) {
+      if (!(obj instanceof MyParameterizedType<?>)) {
         return false;
       }
-      if (getClass() != obj.getClass()) {
-        return false;
-      }
-      MyParameterizedType<T> other = (MyParameterizedType<T>) obj;
-      if (value == null) {
-        if (other.value != null) {
-          return false;
-        }
-      } else if (!value.equals(other.value)) {
-        return false;
-      }
-      return true;
+      MyParameterizedType<?> that = (MyParameterizedType<?>) obj;
+      return Objects.equal(getValue(), that.getValue());
     }
   }
 
@@ -112,8 +102,6 @@ public class ParameterizedTypeFixtures {
      * This means that the fields of the same objects will be overwritten by Gson.
      * This is usually fine in tests since there we deserialize just once, but quite
      * dangerous in practice.
-     *
-     * @param instanceOfT
      */
     public MyParameterizedTypeInstanceCreator(T instanceOfT) {
       this.instanceOfT = instanceOfT;
diff --git a/gson/src/test/java/com/google/gson/VersionExclusionStrategyTest.java b/gson/src/test/java/com/google/gson/VersionExclusionStrategyTest.java
index 9ae8c656..2c644964 100644
--- a/gson/src/test/java/com/google/gson/VersionExclusionStrategyTest.java
+++ b/gson/src/test/java/com/google/gson/VersionExclusionStrategyTest.java
@@ -18,6 +18,7 @@ package com.google.gson;
 
 import static com.google.common.truth.Truth.assertThat;
 
+import com.google.errorprone.annotations.Keep;
 import com.google.gson.annotations.Since;
 import com.google.gson.annotations.Until;
 import com.google.gson.internal.Excluder;
@@ -75,6 +76,7 @@ public class VersionExclusionStrategyTest {
   private static class MockClassSince {
 
     @Since(VERSION)
+    @Keep
     public final int someField = 0;
   }
 
@@ -82,6 +84,7 @@ public class VersionExclusionStrategyTest {
   private static class MockClassUntil {
 
     @Until(VERSION)
+    @Keep
     public final int someField = 0;
   }
 
@@ -91,6 +94,7 @@ public class VersionExclusionStrategyTest {
 
     @Since(VERSION)
     @Until(VERSION + 2)
+    @Keep
     public final int someField = 0;
   }
 }
diff --git a/gson/src/test/java/com/google/gson/common/TestTypes.java b/gson/src/test/java/com/google/gson/common/TestTypes.java
index 9df4a73d..303d6281 100644
--- a/gson/src/test/java/com/google/gson/common/TestTypes.java
+++ b/gson/src/test/java/com/google/gson/common/TestTypes.java
@@ -16,6 +16,7 @@
 
 package com.google.gson.common;
 
+import com.google.common.base.Objects;
 import com.google.gson.JsonDeserializationContext;
 import com.google.gson.JsonDeserializer;
 import com.google.gson.JsonElement;
@@ -146,26 +147,18 @@ public class TestTypes {
     }
 
     @Override
-    public boolean equals(Object obj) {
-      if (this == obj)
+    public boolean equals(Object o) {
+      if (this == o) {
         return true;
-      if (obj == null)
+      }
+      if (!(o instanceof BagOfPrimitives)) {
         return false;
-      if (getClass() != obj.getClass())
-        return false;
-      BagOfPrimitives other = (BagOfPrimitives) obj;
-      if (booleanValue != other.booleanValue)
-        return false;
-      if (intValue != other.intValue)
-        return false;
-      if (longValue != other.longValue)
-        return false;
-      if (stringValue == null) {
-        if (other.stringValue != null)
-          return false;
-      } else if (!stringValue.equals(other.stringValue))
-        return false;
-      return true;
+      }
+      BagOfPrimitives that = (BagOfPrimitives) o;
+      return longValue == that.longValue
+          && getIntValue() == that.getIntValue()
+          && booleanValue == that.booleanValue
+          && Objects.equal(stringValue, that.stringValue);
     }
 
     @Override
@@ -233,7 +226,7 @@ public class TestTypes {
     // Nothing here..
     @Override
     public boolean equals(Object other) {
-      return other.getClass() == ClassWithNoFields.class;
+      return other instanceof ClassWithNoFields;
     }
   }
 
diff --git a/gson/src/test/java/com/google/gson/functional/CollectionTest.java b/gson/src/test/java/com/google/gson/functional/CollectionTest.java
index 3507c94d..afa6e099 100644
--- a/gson/src/test/java/com/google/gson/functional/CollectionTest.java
+++ b/gson/src/test/java/com/google/gson/functional/CollectionTest.java
@@ -93,6 +93,7 @@ public class CollectionTest {
   }
 
   @Test
+  @SuppressWarnings("JdkObsolete")
   public void testLinkedListSerialization() {
     List<String> list = new LinkedList<>();
     list.add("a1");
@@ -113,6 +114,7 @@ public class CollectionTest {
   }
 
   @Test
+  @SuppressWarnings("JdkObsolete")
   public void testQueueSerialization() {
     Queue<String> queue = new LinkedList<>();
     queue.add("a1");
@@ -266,11 +268,11 @@ public class CollectionTest {
   }
 
   @Test
-  public void testRawCollectionDeserializationNotAlllowed() {
+  public void testRawCollectionDeserializationNotAllowed() {
     String json = "[0,1,2,3,4,5,6,7,8,9]";
     Collection<?> integers = gson.fromJson(json, Collection.class);
     // JsonReader converts numbers to double by default so we need a floating point comparison
-    assertThat(integers).isEqualTo(Arrays.asList(0.0, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0));
+    assertThat(integers).containsExactly(0.0, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0).inOrder();
 
     json = "[\"Hello\", \"World\"]";
     Collection<?> strings = gson.fromJson(json, Collection.class);
@@ -416,9 +418,9 @@ public class CollectionTest {
     }
   }
 
-  private class BigClass { private Map<String, ? extends List<SmallClass>> inBig; }
+  private static class BigClass { private Map<String, ? extends List<SmallClass>> inBig; }
 
-  private class SmallClass { private String inSmall; }
+  private static class SmallClass { private String inSmall; }
 
   @Test
   public void testIssue1107() {
diff --git a/gson/src/test/java/com/google/gson/functional/CustomDeserializerTest.java b/gson/src/test/java/com/google/gson/functional/CustomDeserializerTest.java
index 0ee5d860..2813032b 100644
--- a/gson/src/test/java/com/google/gson/functional/CustomDeserializerTest.java
+++ b/gson/src/test/java/com/google/gson/functional/CustomDeserializerTest.java
@@ -130,6 +130,7 @@ public class CustomDeserializerTest {
     static final String TYPE_ACCESS = "__type__";
   }
 
+  @SuppressWarnings("ImmutableEnumChecker")
   private enum SubTypes {
     SUB_TYPE1(SubType1.class),
     SUB_TYPE2(SubType2.class);
diff --git a/gson/src/test/java/com/google/gson/functional/CustomTypeAdaptersTest.java b/gson/src/test/java/com/google/gson/functional/CustomTypeAdaptersTest.java
index 3c59cb81..d398e936 100644
--- a/gson/src/test/java/com/google/gson/functional/CustomTypeAdaptersTest.java
+++ b/gson/src/test/java/com/google/gson/functional/CustomTypeAdaptersTest.java
@@ -17,6 +17,7 @@ package com.google.gson.functional;
 
 import static com.google.common.truth.Truth.assertThat;
 
+import com.google.common.base.Splitter;
 import com.google.gson.Gson;
 import com.google.gson.GsonBuilder;
 import com.google.gson.InstanceCreator;
@@ -35,6 +36,7 @@ import java.lang.reflect.Type;
 import java.util.Date;
 import java.util.HashMap;
 import java.util.HashSet;
+import java.util.List;
 import java.util.Map;
 import java.util.Set;
 import org.junit.Before;
@@ -291,9 +293,9 @@ public class CustomTypeAdaptersTest {
     String part2;
 
     public StringHolder(String string) {
-      String[] parts = string.split(":");
-      part1 = parts[0];
-      part2 = parts[1];
+      List<String> parts = Splitter.on(':').splitToList(string);
+      part1 = parts.get(0);
+      part2 = parts.get(1);
     }
     public StringHolder(String part1, String part2) {
       this.part1 = part1;
@@ -425,6 +427,7 @@ public class CustomTypeAdaptersTest {
 
   // Test created from Issue 352
   @Test
+  @SuppressWarnings({"JavaUtilDate", "UndefinedEquals"})
   public void testRegisterHierarchyAdapterForDate() {
     Gson gson = new GsonBuilder()
         .registerTypeHierarchyAdapter(Date.class, new DateTypeAdapter())
@@ -473,6 +476,7 @@ public class CustomTypeAdaptersTest {
     }
   }
 
+  @SuppressWarnings("JavaUtilDate")
   private static class DateTypeAdapter implements JsonSerializer<Date>, JsonDeserializer<Date> {
     @Override
     public Date deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context) {
diff --git a/gson/src/test/java/com/google/gson/functional/DefaultTypeAdaptersTest.java b/gson/src/test/java/com/google/gson/functional/DefaultTypeAdaptersTest.java
index ee15bfc4..978b0eb8 100644
--- a/gson/src/test/java/com/google/gson/functional/DefaultTypeAdaptersTest.java
+++ b/gson/src/test/java/com/google/gson/functional/DefaultTypeAdaptersTest.java
@@ -68,6 +68,7 @@ import org.junit.Test;
  * @author Inderjeet Singh
  * @author Joel Leitch
  */
+@SuppressWarnings("JavaUtilDate")
 public class DefaultTypeAdaptersTest {
   private Gson gson;
   private TimeZone oldTimeZone;
@@ -700,6 +701,7 @@ public class DefaultTypeAdaptersTest {
   }
 
   @Test
+  @SuppressWarnings("JdkObsolete")
   public void testStringBufferSerialization() {
     StringBuffer sb = new StringBuffer("abc");
     String json = gson.toJson(sb);
diff --git a/gson/src/test/java/com/google/gson/functional/DelegateTypeAdapterTest.java b/gson/src/test/java/com/google/gson/functional/DelegateTypeAdapterTest.java
index 32cf8680..bdfa44c5 100644
--- a/gson/src/test/java/com/google/gson/functional/DelegateTypeAdapterTest.java
+++ b/gson/src/test/java/com/google/gson/functional/DelegateTypeAdapterTest.java
@@ -56,7 +56,7 @@ public class DelegateTypeAdapterTest {
       bags.add(new BagOfPrimitives(i, i, i % 2 == 0, String.valueOf(i)));
     }
     String json = gson.toJson(bags);
-    bags = gson.fromJson(json, new TypeToken<List<BagOfPrimitives>>(){}.getType());
+    gson.fromJson(json, new TypeToken<List<BagOfPrimitives>>(){}.getType());
     // 11: 1 list object, and 10 entries. stats invoked on all 5 fields
     assertThat(stats.numReads).isEqualTo(51);
     assertThat(stats.numWrites).isEqualTo(51);
@@ -66,7 +66,7 @@ public class DelegateTypeAdapterTest {
   public void testDelegateInvokedOnStrings() {
     String[] bags = {"1", "2", "3", "4"};
     String json = gson.toJson(bags);
-    bags = gson.fromJson(json, String[].class);
+    gson.fromJson(json, String[].class);
     // 1 array object with 4 elements.
     assertThat(stats.numReads).isEqualTo(5);
     assertThat(stats.numWrites).isEqualTo(5);
diff --git a/gson/src/test/java/com/google/gson/functional/EnumTest.java b/gson/src/test/java/com/google/gson/functional/EnumTest.java
index 0a9d0cde..0ca4acdf 100644
--- a/gson/src/test/java/com/google/gson/functional/EnumTest.java
+++ b/gson/src/test/java/com/google/gson/functional/EnumTest.java
@@ -120,8 +120,9 @@ public class EnumTest {
    * Test for issue 226.
    */
   @Test
+  @SuppressWarnings("GetClassOnEnum")
   public void testEnumSubclass() {
-    assertThat(Roshambo.ROCK.getClass()).isAssignableTo(Roshambo.class);
+    assertThat(Roshambo.ROCK.getClass()).isNotEqualTo(Roshambo.class);
     assertThat(gson.toJson(Roshambo.ROCK)).isEqualTo("\"ROCK\"");
     assertThat(gson.toJson(EnumSet.allOf(Roshambo.class))).isEqualTo("[\"ROCK\",\"PAPER\",\"SCISSORS\"]");
     assertThat(gson.fromJson("\"ROCK\"", Roshambo.class)).isEqualTo(Roshambo.ROCK);
@@ -131,11 +132,12 @@ public class EnumTest {
   }
 
   @Test
+  @SuppressWarnings("GetClassOnEnum")
   public void testEnumSubclassWithRegisteredTypeAdapter() {
     gson = new GsonBuilder()
         .registerTypeHierarchyAdapter(Roshambo.class, new MyEnumTypeAdapter())
         .create();
-    assertThat(Roshambo.ROCK.getClass()).isAssignableTo(Roshambo.class);
+    assertThat(Roshambo.ROCK.getClass()).isNotEqualTo(Roshambo.class);
     assertThat(gson.toJson(Roshambo.ROCK)).isEqualTo("\"123ROCK\"");
     assertThat(gson.toJson(EnumSet.allOf(Roshambo.class))).isEqualTo("[\"123ROCK\",\"123PAPER\",\"123SCISSORS\"]");
     assertThat(gson.fromJson("\"123ROCK\"", Roshambo.class)).isEqualTo(Roshambo.ROCK);
@@ -207,6 +209,7 @@ public class EnumTest {
       }
     };
 
+    @SuppressWarnings("unused")
     abstract Roshambo defeats();
   }
 
@@ -239,8 +242,8 @@ public class EnumTest {
 
   private enum Color {
     RED("red", 1), BLUE("blue", 2), GREEN("green", 3);
-    String value;
-    int index;
+    final String value;
+    final int index;
     private Color(String value, int index) {
       this.value = value;
       this.index = index;
diff --git a/gson/src/test/java/com/google/gson/functional/EscapingTest.java b/gson/src/test/java/com/google/gson/functional/EscapingTest.java
index deaca904..952e3582 100644
--- a/gson/src/test/java/com/google/gson/functional/EscapingTest.java
+++ b/gson/src/test/java/com/google/gson/functional/EscapingTest.java
@@ -70,7 +70,7 @@ public class EscapingTest {
     assertThat(jsonRepresentation).contains("\\\"");
 
     BagOfPrimitives expectedObject = gson.fromJson(jsonRepresentation, BagOfPrimitives.class);
-    assertThat(expectedObject.getExpectedJson()).isEqualTo(objWithPrimitives.getExpectedJson());
+    assertThat(objWithPrimitives.getExpectedJson()).isEqualTo(expectedObject.getExpectedJson());
   }
   
   @Test
diff --git a/gson/src/test/java/com/google/gson/functional/ExposeFieldsTest.java b/gson/src/test/java/com/google/gson/functional/ExposeFieldsTest.java
index 3215efdf..3b1119b6 100644
--- a/gson/src/test/java/com/google/gson/functional/ExposeFieldsTest.java
+++ b/gson/src/test/java/com/google/gson/functional/ExposeFieldsTest.java
@@ -18,6 +18,7 @@ package com.google.gson.functional;
 
 import static com.google.common.truth.Truth.assertThat;
 
+import com.google.errorprone.annotations.Keep;
 import com.google.gson.Gson;
 import com.google.gson.GsonBuilder;
 import com.google.gson.InstanceCreator;
@@ -121,9 +122,14 @@ public class ExposeFieldsTest {
   private static class ClassWithExposedFields {
     @Expose private final Integer a;
     private final Integer b;
-    @Expose(serialize = false) final long c;
-    @Expose(deserialize = false) final double d;
-    @Expose(serialize = false, deserialize = false) final char e;
+    @Expose(serialize = false)
+    @Keep
+    final long c;
+    @Expose(deserialize = false)
+    final double d;
+    @Expose(serialize = false, deserialize = false)
+    @Keep
+    final char e;
 
     public ClassWithExposedFields(Integer a, Integer b) {
       this(a, b, 1L, 2.0, 'a');
diff --git a/gson/src/test/java/com/google/gson/functional/FieldExclusionTest.java b/gson/src/test/java/com/google/gson/functional/FieldExclusionTest.java
index a1f3e949..7904776e 100644
--- a/gson/src/test/java/com/google/gson/functional/FieldExclusionTest.java
+++ b/gson/src/test/java/com/google/gson/functional/FieldExclusionTest.java
@@ -75,6 +75,8 @@ public class FieldExclusionTest {
   }
 
   private static class Outer {
+
+    @SuppressWarnings("ClassCanBeStatic")
     private class Inner extends NestedClass {
       public Inner(String value) {
         super(value);
diff --git a/gson/src/test/java/com/google/gson/functional/GsonVersionDiagnosticsTest.java b/gson/src/test/java/com/google/gson/functional/GsonVersionDiagnosticsTest.java
index df73d729..b7029487 100644
--- a/gson/src/test/java/com/google/gson/functional/GsonVersionDiagnosticsTest.java
+++ b/gson/src/test/java/com/google/gson/functional/GsonVersionDiagnosticsTest.java
@@ -16,14 +16,13 @@
 package com.google.gson.functional;
 
 import static com.google.common.truth.Truth.assertThat;
-import static org.junit.Assert.fail;
+import static org.junit.Assert.assertThrows;
 
 import com.google.gson.Gson;
 import com.google.gson.GsonBuilder;
 import com.google.gson.TypeAdapter;
 import com.google.gson.stream.JsonReader;
 import com.google.gson.stream.JsonWriter;
-import java.io.IOException;
 import java.util.regex.Pattern;
 import org.junit.Before;
 import org.junit.Test;
@@ -46,7 +45,7 @@ public class GsonVersionDiagnosticsTest {
       @Override public void write(JsonWriter out, TestType value) {
         throw new AssertionError("Expected during serialization");
       }
-      @Override public TestType read(JsonReader in) throws IOException {
+      @Override public TestType read(JsonReader in) {
         throw new AssertionError("Expected during deserialization");
       }
     }).create();
@@ -60,22 +59,16 @@ public class GsonVersionDiagnosticsTest {
 
   @Test
   public void testAssertionErrorInSerializationPrintsVersion() {
-    try {
-      gson.toJson(new TestType());
-      fail();
-    } catch (AssertionError expected) {
-      ensureAssertionErrorPrintsGsonVersion(expected);
-    }
+    AssertionError e = assertThrows(AssertionError.class, () -> gson.toJson(new TestType()));
+    ensureAssertionErrorPrintsGsonVersion(e);
   }
 
   @Test
   public void testAssertionErrorInDeserializationPrintsVersion() {
-    try {
-      gson.fromJson("{'a':'abc'}", TestType.class);
-      fail();
-    } catch (AssertionError expected) {
-      ensureAssertionErrorPrintsGsonVersion(expected);
-    }
+    AssertionError e = assertThrows(AssertionError.class,
+        () -> gson.fromJson("{'a':'abc'}", TestType.class));
+
+    ensureAssertionErrorPrintsGsonVersion(e);
   }
 
   private void ensureAssertionErrorPrintsGsonVersion(AssertionError expected) {
diff --git a/gson/src/test/java/com/google/gson/functional/InheritanceTest.java b/gson/src/test/java/com/google/gson/functional/InheritanceTest.java
index a4f8c873..ec7cdde8 100644
--- a/gson/src/test/java/com/google/gson/functional/InheritanceTest.java
+++ b/gson/src/test/java/com/google/gson/functional/InheritanceTest.java
@@ -162,6 +162,7 @@ public class InheritanceTest {
   }
 
   @Test
+  @SuppressWarnings("JdkObsolete")
   public void testSubInterfacesOfCollectionSerialization() {
     List<Integer> list = new LinkedList<>();
     list.add(0);
diff --git a/gson/src/test/java/com/google/gson/functional/Java17RecordTest.java b/gson/src/test/java/com/google/gson/functional/Java17RecordTest.java
index 93a2224c..0b9a6c07 100644
--- a/gson/src/test/java/com/google/gson/functional/Java17RecordTest.java
+++ b/gson/src/test/java/com/google/gson/functional/Java17RecordTest.java
@@ -72,6 +72,7 @@ public final class Java17RecordTest {
         .isEqualTo("v3");
   }
 
+  @SuppressWarnings("unused")
   private record RecordWithCustomNames(
       @SerializedName("name") String a,
       @SerializedName(value = "name1", alternate = {"name2", "name3"}) String b) {}
@@ -135,6 +136,7 @@ public final class Java17RecordTest {
 
   /** Tests behavior when the canonical constructor throws an exception */
   @Test
+  @SuppressWarnings("StaticAssignmentOfThrowable")
   public void testThrowingConstructor() {
     record LocalRecord(String s) {
       static final RuntimeException thrownException = new RuntimeException("Custom exception");
@@ -171,6 +173,7 @@ public final class Java17RecordTest {
 
   /** Tests behavior when a record accessor method throws an exception */
   @Test
+  @SuppressWarnings("StaticAssignmentOfThrowable")
   public void testThrowingAccessor() {
     record LocalRecord(String s) {
       static final RuntimeException thrownException = new RuntimeException("Custom exception");
@@ -253,6 +256,7 @@ public final class Java17RecordTest {
         .isEqualTo("null is not allowed as value for record component 'aByte' of primitive type; at path $.aByte");
   }
 
+  @SuppressWarnings("unused")
   private record RecordWithPrimitives(
       String aString, byte aByte, short aShort, int anInt, long aLong, float aFloat, double aDouble, char aChar, boolean aBoolean) {}
 
@@ -406,7 +410,9 @@ public final class Java17RecordTest {
     assertThat(gson.fromJson("{\"i\":2}", PublicRecord.class)).isEqualTo(new PublicRecord(2));
   }
 
+  @SuppressWarnings("unused")
   private record PrivateRecord(int i) {}
+  @SuppressWarnings("unused")
   public record PublicRecord(int i) {}
 
   /**
diff --git a/gson/src/test/java/com/google/gson/functional/JsonAdapterAnnotationOnClassesTest.java b/gson/src/test/java/com/google/gson/functional/JsonAdapterAnnotationOnClassesTest.java
index 4731f0df..3edd8d79 100644
--- a/gson/src/test/java/com/google/gson/functional/JsonAdapterAnnotationOnClassesTest.java
+++ b/gson/src/test/java/com/google/gson/functional/JsonAdapterAnnotationOnClassesTest.java
@@ -19,6 +19,7 @@ package com.google.gson.functional;
 import static com.google.common.truth.Truth.assertThat;
 import static org.junit.Assert.fail;
 
+import com.google.common.base.Splitter;
 import com.google.gson.Gson;
 import com.google.gson.GsonBuilder;
 import com.google.gson.JsonDeserializationContext;
@@ -36,6 +37,7 @@ import com.google.gson.stream.JsonReader;
 import com.google.gson.stream.JsonWriter;
 import java.io.IOException;
 import java.lang.reflect.Type;
+import java.util.List;
 import java.util.Locale;
 import org.junit.Test;
 
@@ -226,9 +228,9 @@ public final class JsonAdapterAnnotationOnClassesTest {
       // implement read: split name into firstName and lastName
       in.beginObject();
       in.nextName();
-      String[] nameParts = in.nextString().split(" ");
+      List<String> nameParts = Splitter.on(" ").splitToList(in.nextString());
       in.endObject();
-      return new User(nameParts[0], nameParts[1]);
+      return new User(nameParts.get(0), nameParts.get(1));
     }
   }
 
diff --git a/gson/src/test/java/com/google/gson/functional/JsonAdapterSerializerDeserializerTest.java b/gson/src/test/java/com/google/gson/functional/JsonAdapterSerializerDeserializerTest.java
index 1c06a3ba..20081f68 100644
--- a/gson/src/test/java/com/google/gson/functional/JsonAdapterSerializerDeserializerTest.java
+++ b/gson/src/test/java/com/google/gson/functional/JsonAdapterSerializerDeserializerTest.java
@@ -18,6 +18,7 @@ package com.google.gson.functional;
 
 import static com.google.common.truth.Truth.assertThat;
 
+import com.google.errorprone.annotations.Keep;
 import com.google.gson.Gson;
 import com.google.gson.JsonDeserializationContext;
 import com.google.gson.JsonDeserializer;
@@ -47,9 +48,15 @@ public final class JsonAdapterSerializerDeserializerTest {
   }
 
   private static final class Computer {
-    @JsonAdapter(UserSerializer.class) final User user1;
-    @JsonAdapter(UserDeserializer.class) final User user2;
-    @JsonAdapter(UserSerializerDeserializer.class) final User user3;
+    @JsonAdapter(UserSerializer.class)
+    @Keep
+    final User user1;
+    @JsonAdapter(UserDeserializer.class)
+    @Keep
+    final User user2;
+    @JsonAdapter(UserSerializerDeserializer.class)
+    @Keep
+    final User user3;
     Computer(User user1, User user2, User user3) {
       this.user1 = user1;
       this.user2 = user2;
@@ -137,8 +144,12 @@ public final class JsonAdapterSerializerDeserializerTest {
   }
 
   private static final class Container {
-    @JsonAdapter(BaseStringAdapter.class) Base<String> a;
-    @JsonAdapter(BaseIntegerAdapter.class) Base<Integer> b;
+    @JsonAdapter(BaseStringAdapter.class)
+    @Keep
+    Base<String> a;
+    @JsonAdapter(BaseIntegerAdapter.class)
+    @Keep
+    Base<Integer> b;
     Container(String a, int b) {
       this.a = new Base<>(a);
       this.b = new Base<>(b);
diff --git a/gson/src/test/java/com/google/gson/functional/ObjectTest.java b/gson/src/test/java/com/google/gson/functional/ObjectTest.java
index 23a1ef20..47eaf9df 100644
--- a/gson/src/test/java/com/google/gson/functional/ObjectTest.java
+++ b/gson/src/test/java/com/google/gson/functional/ObjectTest.java
@@ -161,7 +161,7 @@ public class ObjectTest {
   private static class Subclass extends Superclass1 {
   }
   private static class Superclass1 extends Superclass2 {
-    @SuppressWarnings("unused")
+    @SuppressWarnings({"unused", "HidingField"})
     String s;
   }
   private static class Superclass2 {
@@ -414,6 +414,8 @@ public class ObjectTest {
   private static class Parent {
     @SuppressWarnings("unused")
     int value1 = 1;
+
+    @SuppressWarnings("ClassCanBeStatic")
     private class Child {
       int value2 = 2;
     }
@@ -562,6 +564,7 @@ public class ObjectTest {
 
   // http://code.google.com/p/google-gson/issues/detail?id=270
   @Test
+  @SuppressWarnings("JavaUtilDate")
   public void testDateAsMapObjectField() {
     HasObjectMap a = new HasObjectMap();
     a.map.put("date", new Date(0));
@@ -654,6 +657,7 @@ public class ObjectTest {
     }
   }
 
+  @SuppressWarnings("StaticAssignmentOfThrowable")
   static class ClassWithThrowingConstructor {
     static final RuntimeException thrownException = new RuntimeException("Custom exception");
 
diff --git a/gson/src/test/java/com/google/gson/functional/ParameterizedTypesTest.java b/gson/src/test/java/com/google/gson/functional/ParameterizedTypesTest.java
index 53bb6f77..daf049dc 100644
--- a/gson/src/test/java/com/google/gson/functional/ParameterizedTypesTest.java
+++ b/gson/src/test/java/com/google/gson/functional/ParameterizedTypesTest.java
@@ -18,6 +18,7 @@ package com.google.gson.functional;
 
 import static com.google.common.truth.Truth.assertThat;
 
+import com.google.common.base.Objects;
 import com.google.gson.Gson;
 import com.google.gson.GsonBuilder;
 import com.google.gson.JsonArray;
@@ -399,7 +400,7 @@ public class ParameterizedTypesTest {
     }
   }
 
-  private static class MultiParameters<A, B, C, D, E> {
+  private static final class MultiParameters<A, B, C, D, E> {
     A a;
     B b;
     C c;
@@ -429,54 +430,19 @@ public class ParameterizedTypesTest {
       return result;
     }
     @Override
-    @SuppressWarnings("unchecked")
-    public boolean equals(Object obj) {
-      if (this == obj) {
+    public boolean equals(Object o) {
+      if (this == o) {
         return true;
       }
-      if (obj == null) {
+      if (!(o instanceof MultiParameters<?, ?, ?, ?, ?>)) {
         return false;
       }
-      if (getClass() != obj.getClass()) {
-        return false;
-      }
-      MultiParameters<A, B, C, D, E> other = (MultiParameters<A, B, C, D, E>) obj;
-      if (a == null) {
-        if (other.a != null) {
-          return false;
-        }
-      } else if (!a.equals(other.a)) {
-        return false;
-      }
-      if (b == null) {
-        if (other.b != null) {
-          return false;
-        }
-      } else if (!b.equals(other.b)) {
-        return false;
-      }
-      if (c == null) {
-        if (other.c != null) {
-          return false;
-        }
-      } else if (!c.equals(other.c)) {
-        return false;
-      }
-      if (d == null) {
-        if (other.d != null) {
-          return false;
-        }
-      } else if (!d.equals(other.d)) {
-        return false;
-      }
-      if (e == null) {
-        if (other.e != null) {
-          return false;
-        }
-      } else if (!e.equals(other.e)) {
-        return false;
-      }
-      return true;
+      MultiParameters<?, ?, ?, ?, ?> that = (MultiParameters<?, ?, ?, ?, ?>) o;
+      return Objects.equal(a, that.a)
+          && Objects.equal(b, that.b)
+          && Objects.equal(c, that.c)
+          && Objects.equal(d, that.d)
+          && Objects.equal(e, that.e);
     }
   }
 
diff --git a/gson/src/test/java/com/google/gson/functional/PrettyPrintingTest.java b/gson/src/test/java/com/google/gson/functional/PrettyPrintingTest.java
index 52b94490..54960651 100644
--- a/gson/src/test/java/com/google/gson/functional/PrettyPrintingTest.java
+++ b/gson/src/test/java/com/google/gson/functional/PrettyPrintingTest.java
@@ -23,6 +23,7 @@ import com.google.gson.common.TestTypes.ArrayOfObjects;
 import com.google.gson.common.TestTypes.BagOfPrimitives;
 import com.google.gson.reflect.TypeToken;
 import java.lang.reflect.Type;
+import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.LinkedHashMap;
 import java.util.LinkedList;
@@ -51,7 +52,7 @@ public class PrettyPrintingTest {
   @Test
   public void testPrettyPrintList() {
     BagOfPrimitives b = new BagOfPrimitives();
-    List<BagOfPrimitives> listOfB = new LinkedList<>();
+    List<BagOfPrimitives> listOfB = new ArrayList<>();
     for (int i = 0; i < 15; ++i) {
       listOfB.add(b);
     }
diff --git a/gson/src/test/java/com/google/gson/functional/PrimitiveTest.java b/gson/src/test/java/com/google/gson/functional/PrimitiveTest.java
index bfb31915..f7bccb46 100644
--- a/gson/src/test/java/com/google/gson/functional/PrimitiveTest.java
+++ b/gson/src/test/java/com/google/gson/functional/PrimitiveTest.java
@@ -192,7 +192,7 @@ public class PrimitiveTest {
     // Should perform widening conversion
     assertThat(gson.toJson((byte) 1, Float.class)).isEqualTo("1.0");
     // (This widening conversion is actually lossy)
-    assertThat(gson.toJson(Long.MAX_VALUE - 10L, Float.class)).isEqualTo(Float.toString(Long.MAX_VALUE - 10L));
+    assertThat(gson.toJson(Long.MAX_VALUE - 10L, Float.class)).isEqualTo(Float.toString((float) (Long.MAX_VALUE - 10L)));
     // Should perform narrowing conversion
     gson = new GsonBuilder().serializeSpecialFloatingPointValues().create();
     assertThat(gson.toJson(Double.MAX_VALUE, Float.class)).isEqualTo("Infinity");
@@ -207,7 +207,7 @@ public class PrimitiveTest {
     // Should perform widening conversion
     assertThat(gson.toJson((byte) 1, Double.class)).isEqualTo("1.0");
     // (This widening conversion is actually lossy)
-    assertThat(gson.toJson(Long.MAX_VALUE - 10L, Double.class)).isEqualTo(Double.toString(Long.MAX_VALUE - 10L));
+    assertThat(gson.toJson(Long.MAX_VALUE - 10L, Double.class)).isEqualTo(Double.toString((double) (Long.MAX_VALUE - 10L)));
   }
 
   @Test
diff --git a/gson/src/test/java/com/google/gson/functional/PrintFormattingTest.java b/gson/src/test/java/com/google/gson/functional/PrintFormattingTest.java
index d31a43d0..bd53944f 100644
--- a/gson/src/test/java/com/google/gson/functional/PrintFormattingTest.java
+++ b/gson/src/test/java/com/google/gson/functional/PrintFormattingTest.java
@@ -78,6 +78,7 @@ public class PrintFormattingTest {
     assertThat(json).contains("field2");
   }
 
+  @SuppressWarnings("LoopOverCharArray")
   private static void assertContainsNoWhiteSpace(String str) {
     for (char c : str.toCharArray()) {
       assertThat(Character.isWhitespace(c)).isFalse();
diff --git a/gson/src/test/java/com/google/gson/functional/ReflectionAccessTest.java b/gson/src/test/java/com/google/gson/functional/ReflectionAccessTest.java
index f552a5fc..75660360 100644
--- a/gson/src/test/java/com/google/gson/functional/ReflectionAccessTest.java
+++ b/gson/src/test/java/com/google/gson/functional/ReflectionAccessTest.java
@@ -130,7 +130,7 @@ public class ReflectionAccessTest {
       gson.fromJson("[]", internalClass);
       fail("Missing exception; test has to be run with `--illegal-access=deny`");
     } catch (JsonSyntaxException e) {
-      fail("Unexpected exception; test has to be run with `--illegal-access=deny`");
+      throw new AssertionError("Unexpected exception; test has to be run with `--illegal-access=deny`", e);
     } catch (JsonIOException expected) {
       assertThat(expected).hasMessageThat().startsWith("Failed making constructor 'java.util.Collections$EmptyList()' accessible;"
           + " either increase its visibility or write a custom InstanceCreator or TypeAdapter for its declaring type: ");
diff --git a/gson/src/test/java/com/google/gson/functional/StreamingTypeAdaptersTest.java b/gson/src/test/java/com/google/gson/functional/StreamingTypeAdaptersTest.java
index 6e13624f..fecc828f 100644
--- a/gson/src/test/java/com/google/gson/functional/StreamingTypeAdaptersTest.java
+++ b/gson/src/test/java/com/google/gson/functional/StreamingTypeAdaptersTest.java
@@ -20,6 +20,7 @@ import static com.google.common.truth.Truth.assertThat;
 import static com.google.common.truth.Truth.assertWithMessage;
 import static org.junit.Assert.fail;
 
+import com.google.common.base.Splitter;
 import com.google.gson.Gson;
 import com.google.gson.GsonBuilder;
 import com.google.gson.JsonArray;
@@ -172,8 +173,8 @@ public final class StreamingTypeAdaptersTest {
   public void testNullSafe() {
     TypeAdapter<Person> typeAdapter = new TypeAdapter<Person>() {
       @Override public Person read(JsonReader in) throws IOException {
-        String[] values = in.nextString().split(",");
-        return new Person(values[0], Integer.parseInt(values[1]));
+        List<String> values = Splitter.on(',').splitToList(in.nextString());
+        return new Person(values.get(0), Integer.parseInt(values.get(1)));
       }
       @Override public void write(JsonWriter out, Person person) throws IOException {
         out.value(person.name + "," + person.age);
diff --git a/gson/src/test/java/com/google/gson/functional/StringTest.java b/gson/src/test/java/com/google/gson/functional/StringTest.java
index e92b2da9..b702ef5c 100644
--- a/gson/src/test/java/com/google/gson/functional/StringTest.java
+++ b/gson/src/test/java/com/google/gson/functional/StringTest.java
@@ -154,7 +154,7 @@ public class StringTest {
     String value = gson.fromJson(json, String.class);
     assertThat(value).isEqualTo("abc=");
 
-    json = "'abc\u003d'";
+    json = "'abc\\u003d'";
     value = gson.fromJson(json, String.class);
     assertThat(value).isEqualTo("abc=");
   }
diff --git a/gson/src/test/java/com/google/gson/functional/ToNumberPolicyFunctionalTest.java b/gson/src/test/java/com/google/gson/functional/ToNumberPolicyFunctionalTest.java
index d500546f..aba9edd5 100644
--- a/gson/src/test/java/com/google/gson/functional/ToNumberPolicyFunctionalTest.java
+++ b/gson/src/test/java/com/google/gson/functional/ToNumberPolicyFunctionalTest.java
@@ -29,7 +29,6 @@ import com.google.gson.stream.JsonReader;
 import java.lang.reflect.Type;
 import java.math.BigDecimal;
 import java.util.Collection;
-import java.util.LinkedList;
 import java.util.List;
 import org.junit.Test;
 
@@ -103,16 +102,12 @@ public class ToNumberPolicyFunctionalTest {
         .setObjectToNumberStrategy(ToNumberPolicy.LONG_OR_DOUBLE)
         .setNumberToNumberStrategy(ToNumberPolicy.LONG_OR_DOUBLE)
         .create();
-    List<Object> expected = new LinkedList<>();
-    expected.add(null);
-    expected.add(10L);
-    expected.add(10.0);
     Type objectCollectionType = new TypeToken<Collection<Object>>() { }.getType();
     Collection<Object> objects = gson.fromJson("[null,10,10.0]", objectCollectionType);
-    assertThat(objects).isEqualTo(expected);
+    assertThat(objects).containsExactly(null, 10L, 10.0).inOrder();
     Type numberCollectionType = new TypeToken<Collection<Number>>() { }.getType();
     Collection<Object> numbers = gson.fromJson("[null,10,10.0]", numberCollectionType);
-    assertThat(numbers).isEqualTo(expected);
+    assertThat(numbers).containsExactly(null, 10L, 10.0).inOrder();
   }
 
   @Test
diff --git a/gson/src/test/java/com/google/gson/functional/TreeTypeAdaptersTest.java b/gson/src/test/java/com/google/gson/functional/TreeTypeAdaptersTest.java
index 9e0382d0..34280e5d 100644
--- a/gson/src/test/java/com/google/gson/functional/TreeTypeAdaptersTest.java
+++ b/gson/src/test/java/com/google/gson/functional/TreeTypeAdaptersTest.java
@@ -79,6 +79,7 @@ public class TreeTypeAdaptersTest {
     assertThat(target.getId().getValue()).isEqualTo("1");
   }
 
+  @SuppressWarnings("UnusedTypeParameter")
   private static final class Id<R> {
     final String value;
     @SuppressWarnings("unused")
diff --git a/gson/src/test/java/com/google/gson/internal/LinkedTreeMapTest.java b/gson/src/test/java/com/google/gson/internal/LinkedTreeMapTest.java
index c811e31b..f79c76b7 100644
--- a/gson/src/test/java/com/google/gson/internal/LinkedTreeMapTest.java
+++ b/gson/src/test/java/com/google/gson/internal/LinkedTreeMapTest.java
@@ -61,6 +61,7 @@ public final class LinkedTreeMapTest {
   }
 
   @Test
+  @SuppressWarnings("ModifiedButNotUsed")
   public void testPutNullKeyFails() {
     LinkedTreeMap<String, String> map = new LinkedTreeMap<>();
     try {
@@ -71,6 +72,7 @@ public final class LinkedTreeMapTest {
   }
 
   @Test
+  @SuppressWarnings("ModifiedButNotUsed")
   public void testPutNonComparableKeyFails() {
     LinkedTreeMap<Object, String> map = new LinkedTreeMap<>();
     try {
@@ -174,12 +176,12 @@ public final class LinkedTreeMapTest {
   }
 
   @Test
-  public void testLargeSetOfRandomKeys() throws Exception {
+  public void testLargeSetOfRandomKeys() {
     Random random = new Random(1367593214724L);
     LinkedTreeMap<String, String> map = new LinkedTreeMap<>();
     String[] keys = new String[1000];
     for (int i = 0; i < keys.length; i++) {
-      keys[i] = Integer.toString(Math.abs(random.nextInt()), 36) + "-" + i;
+      keys[i] = Integer.toString(random.nextInt(), 36) + "-" + i;
       map.put(keys[i], "" + i);
     }
 
diff --git a/gson/src/test/java/com/google/gson/internal/UnsafeAllocatorInstantiationTest.java b/gson/src/test/java/com/google/gson/internal/UnsafeAllocatorInstantiationTest.java
index a80a4c3d..72f830c6 100644
--- a/gson/src/test/java/com/google/gson/internal/UnsafeAllocatorInstantiationTest.java
+++ b/gson/src/test/java/com/google/gson/internal/UnsafeAllocatorInstantiationTest.java
@@ -16,7 +16,7 @@
 package com.google.gson.internal;
 
 import static com.google.common.truth.Truth.assertThat;
-import static org.junit.Assert.fail;
+import static org.junit.Assert.assertThrows;
 
 import org.junit.Test;
 
@@ -40,13 +40,11 @@ public final class UnsafeAllocatorInstantiationTest {
    * to instantiate an interface
    */
   @Test
-  public void testInterfaceInstantiation() throws Exception {
-    try {
-      UnsafeAllocator.INSTANCE.newInstance(Interface.class);
-      fail();
-    } catch (AssertionError e) {
-      assertThat(e).hasMessageThat().startsWith("UnsafeAllocator is used for non-instantiable type");
-    }
+  public void testInterfaceInstantiation() {
+    AssertionError e = assertThrows(AssertionError.class,
+        () -> UnsafeAllocator.INSTANCE.newInstance(Interface.class));
+
+    assertThat(e).hasMessageThat().startsWith("UnsafeAllocator is used for non-instantiable type");
   }
 
   /**
@@ -54,13 +52,11 @@ public final class UnsafeAllocatorInstantiationTest {
    * to instantiate an abstract class
    */
   @Test
-  public void testAbstractClassInstantiation() throws Exception {
-    try {
-      UnsafeAllocator.INSTANCE.newInstance(AbstractClass.class);
-      fail();
-    } catch (AssertionError e) {
-      assertThat(e).hasMessageThat().startsWith("UnsafeAllocator is used for non-instantiable type");
-    }
+  public void testAbstractClassInstantiation() {
+    AssertionError e = assertThrows(AssertionError.class,
+        () -> UnsafeAllocator.INSTANCE.newInstance(AbstractClass.class));
+
+    assertThat(e).hasMessageThat().startsWith("UnsafeAllocator is used for non-instantiable type");
   }
 
   /**
diff --git a/gson/src/test/java/com/google/gson/internal/bind/DefaultDateTypeAdapterTest.java b/gson/src/test/java/com/google/gson/internal/bind/DefaultDateTypeAdapterTest.java
index 99d69e03..2034e38f 100644
--- a/gson/src/test/java/com/google/gson/internal/bind/DefaultDateTypeAdapterTest.java
+++ b/gson/src/test/java/com/google/gson/internal/bind/DefaultDateTypeAdapterTest.java
@@ -39,6 +39,7 @@ import org.junit.Test;
  *
  * @author Joel Leitch
  */
+@SuppressWarnings("JavaUtilDate")
 public class DefaultDateTypeAdapterTest {
 
   @Test
@@ -226,6 +227,7 @@ public class DefaultDateTypeAdapterTest {
     assertThat(adapter.toJson(new Date(0))).isEqualTo(toLiteral(formatted));
   }
 
+  @SuppressWarnings("UndefinedEquals")
   private static void assertParsed(String date, TypeAdapterFactory adapterFactory) throws IOException {
     TypeAdapter<Date> adapter = dateAdapter(adapterFactory);
     assertWithMessage(date).that(adapter.fromJson(toLiteral(date))).isEqualTo(new Date(0));
diff --git a/gson/src/test/java/com/google/gson/internal/bind/util/ISO8601UtilsTest.java b/gson/src/test/java/com/google/gson/internal/bind/util/ISO8601UtilsTest.java
index c96ae643..4a16ee9f 100644
--- a/gson/src/test/java/com/google/gson/internal/bind/util/ISO8601UtilsTest.java
+++ b/gson/src/test/java/com/google/gson/internal/bind/util/ISO8601UtilsTest.java
@@ -57,6 +57,7 @@ public class ISO8601UtilsTest {
     }
 
   @Test
+  @SuppressWarnings("JavaUtilDate")
   public void testDateFormatWithMilliseconds() {
         long time = 1530209176870L;
         Date date = new Date(time);
@@ -66,6 +67,7 @@ public class ISO8601UtilsTest {
     }
 
   @Test
+  @SuppressWarnings("JavaUtilDate")
   public void testDateFormatWithTimezone() {
         long time = 1530209176870L;
         Date date = new Date(time);
@@ -75,6 +77,7 @@ public class ISO8601UtilsTest {
     }
 
   @Test
+  @SuppressWarnings("UndefinedEquals")
   public void testDateParseWithDefaultTimezone() throws ParseException {
         String dateStr = "2018-06-25";
         Date date = ISO8601Utils.parse(dateStr, new ParsePosition(0));
@@ -103,6 +106,7 @@ public class ISO8601UtilsTest {
     }
 
   @Test
+  @SuppressWarnings("UndefinedEquals")
   public void testDateParseWithTimezone() throws ParseException {
         String dateStr = "2018-06-25T00:00:00-03:00";
         Date date = ISO8601Utils.parse(dateStr, new ParsePosition(0));
@@ -113,6 +117,7 @@ public class ISO8601UtilsTest {
     }
 
   @Test
+  @SuppressWarnings("UndefinedEquals")
   public void testDateParseSpecialTimezone() throws ParseException {
         String dateStr = "2018-06-25T00:02:00-02:58";
         Date date = ISO8601Utils.parse(dateStr, new ParsePosition(0));
diff --git a/gson/src/test/java/com/google/gson/reflect/TypeTokenTest.java b/gson/src/test/java/com/google/gson/reflect/TypeTokenTest.java
index 52b2988d..5df759f0 100644
--- a/gson/src/test/java/com/google/gson/reflect/TypeTokenTest.java
+++ b/gson/src/test/java/com/google/gson/reflect/TypeTokenTest.java
@@ -29,6 +29,8 @@ import java.util.Set;
 import org.junit.Test;
 
 /**
+ * Tests for {@link TypeToken}.
+ *
  * @author Jesse Wilson
  */
 public final class TypeTokenTest {
diff --git a/gson/src/test/java/com/google/gson/regression/OSGiTest.java b/gson/src/test/java/com/google/gson/regression/OSGiTest.java
index 000a6731..21b981ae 100644
--- a/gson/src/test/java/com/google/gson/regression/OSGiTest.java
+++ b/gson/src/test/java/com/google/gson/regression/OSGiTest.java
@@ -18,6 +18,7 @@ package com.google.gson.regression;
 import static com.google.common.truth.Truth.assertWithMessage;
 import static org.junit.Assert.fail;
 
+import com.google.common.base.Splitter;
 import java.io.IOException;
 import java.io.InputStream;
 import java.net.URL;
@@ -41,7 +42,7 @@ public class OSGiTest {
         Manifest mf = findManifest("com.google.gson");
         String importPkg = mf.getMainAttributes().getValue("Import-Package");
     assertWithMessage("Import-Package statement is there").that(importPkg).isNotNull();
-        for (String dep : importPkg.split(",")) {
+        for (String dep : Splitter.on(',').split(importPkg)) {
             if (dep.contains("sun.misc")) {
                 assertSubstring("sun.misc import is optional", dep, "resolution:=optional");
                 return;
diff --git a/gson/src/test/java/com/google/gson/stream/JsonReaderTest.java b/gson/src/test/java/com/google/gson/stream/JsonReaderTest.java
index 09c07470..8ebe20b5 100644
--- a/gson/src/test/java/com/google/gson/stream/JsonReaderTest.java
+++ b/gson/src/test/java/com/google/gson/stream/JsonReaderTest.java
@@ -642,6 +642,7 @@ public final class JsonReaderTest {
       strictReader.nextDouble();
       fail("Should have failed reading " + s + " as double");
     } catch (MalformedJsonException e) {
+      assertThat(e).hasMessageThat().startsWith("Use JsonReader.setLenient(true) to accept malformed JSON");
     }
   }
 
@@ -705,7 +706,6 @@ public final class JsonReaderTest {
 
   /**
    * Issue 1053, negative zero.
-   * @throws Exception
    */
   @Test
   public void testNegativeZero() throws Exception {
@@ -741,6 +741,8 @@ public final class JsonReaderTest {
   @Test
   @Ignore
   public void disabled_testPeekLargerThanLongMinValue() throws IOException {
+    @SuppressWarnings("FloatingPointLiteralPrecision")
+    double d = -9223372036854775809d;
     JsonReader reader = new JsonReader(reader("[-9223372036854775809]"));
     reader.setLenient(true);
     reader.beginArray();
@@ -750,7 +752,7 @@ public final class JsonReaderTest {
       fail();
     } catch (NumberFormatException expected) {
     }
-    assertThat(reader.nextDouble()).isEqualTo(-9223372036854775809d);
+    assertThat(reader.nextDouble()).isEqualTo(d);
   }
 
   /**
@@ -769,6 +771,8 @@ public final class JsonReaderTest {
 
   @Test
   public void testPeekMuchLargerThanLongMinValue() throws IOException {
+    @SuppressWarnings("FloatingPointLiteralPrecision")
+    double d = -92233720368547758080d;
     JsonReader reader = new JsonReader(reader("[-92233720368547758080]"));
     reader.setLenient(true);
     reader.beginArray();
@@ -778,12 +782,12 @@ public final class JsonReaderTest {
       fail();
     } catch (NumberFormatException expected) {
     }
-    assertThat(reader.nextDouble()).isEqualTo(-92233720368547758080d);
+    assertThat(reader.nextDouble()).isEqualTo(d);
   }
 
   @Test
   public void testQuotedNumberWithEscape() throws IOException {
-    JsonReader reader = new JsonReader(reader("[\"12\u00334\"]"));
+    JsonReader reader = new JsonReader(reader("[\"12\\u00334\"]"));
     reader.setLenient(true);
     reader.beginArray();
     assertThat(reader.peek()).isEqualTo(STRING);
@@ -2005,6 +2009,7 @@ public final class JsonReaderTest {
           reader.peek();
           fail();
         } catch (IOException expected) {
+          // OK: Should fail
         }
       } else {
         throw new AssertionError();
diff --git a/metrics/src/main/java/com/google/gson/metrics/BagOfPrimitives.java b/metrics/src/main/java/com/google/gson/metrics/BagOfPrimitives.java
index a073974d..1cdc37ea 100644
--- a/metrics/src/main/java/com/google/gson/metrics/BagOfPrimitives.java
+++ b/metrics/src/main/java/com/google/gson/metrics/BagOfPrimitives.java
@@ -15,6 +15,8 @@
  */
 package com.google.gson.metrics;
 
+import com.google.common.base.Objects;
+
 /**
  * Class with a bunch of primitive fields
  *
@@ -63,19 +65,18 @@ public class BagOfPrimitives {
   }
 
   @Override
-  public boolean equals(Object obj) {
-    if (this == obj) return true;
-    if (obj == null) return false;
-    if (getClass() != obj.getClass()) return false;
-    BagOfPrimitives other = (BagOfPrimitives) obj;
-    if (booleanValue != other.booleanValue) return false;
-    if (intValue != other.intValue) return false;
-    if (longValue != other.longValue) return false;
-    if (stringValue == null) {
-      return other.stringValue == null;
-    } else {
-      return stringValue.equals(other.stringValue);
+  public boolean equals(Object o) {
+    if (this == o) {
+      return true;
     }
+    if (!(o instanceof BagOfPrimitives)) {
+      return false;
+    }
+    BagOfPrimitives that = (BagOfPrimitives) o;
+    return longValue == that.longValue
+        && intValue == that.intValue
+        && booleanValue == that.booleanValue
+        && Objects.equal(stringValue, that.stringValue);
   }
 
   @Override
diff --git a/metrics/src/main/java/com/google/gson/metrics/CollectionsDeserializationBenchmark.java b/metrics/src/main/java/com/google/gson/metrics/CollectionsDeserializationBenchmark.java
index 738b5ae4..c10202db 100644
--- a/metrics/src/main/java/com/google/gson/metrics/CollectionsDeserializationBenchmark.java
+++ b/metrics/src/main/java/com/google/gson/metrics/CollectionsDeserializationBenchmark.java
@@ -64,6 +64,7 @@ public class CollectionsDeserializationBenchmark {
   /**
    * Benchmark to measure deserializing objects by hand
    */
+  @SuppressWarnings("ModifiedButNotUsed")
   public void timeCollectionsStreaming(int reps) throws IOException {
     for (int i=0; i<reps; ++i) {
       StringReader reader = new StringReader(json);
@@ -102,6 +103,7 @@ public class CollectionsDeserializationBenchmark {
    * setting object values by reflection. We should strive to reduce the discrepancy between this
    * and {@link #timeCollectionsDefault(int)} .
    */
+  @SuppressWarnings("ModifiedButNotUsed")
   public void timeCollectionsReflectionStreaming(int reps) throws Exception {
     for (int i=0; i<reps; ++i) {
       StringReader reader = new StringReader(json);
diff --git a/metrics/src/main/java/com/google/gson/metrics/ParseBenchmark.java b/metrics/src/main/java/com/google/gson/metrics/ParseBenchmark.java
index 3705ceb0..63522af2 100644
--- a/metrics/src/main/java/com/google/gson/metrics/ParseBenchmark.java
+++ b/metrics/src/main/java/com/google/gson/metrics/ParseBenchmark.java
@@ -38,7 +38,6 @@ import java.io.IOException;
 import java.io.InputStreamReader;
 import java.io.Reader;
 import java.io.StringWriter;
-import java.lang.reflect.Type;
 import java.net.URL;
 import java.nio.charset.StandardCharsets;
 import java.text.SimpleDateFormat;
@@ -64,7 +63,9 @@ public final class ParseBenchmark {
     READER_SHORT(new TypeToken<Feed>() {}, new TypeReference<Feed>() {}),
     READER_LONG(new TypeToken<Feed>() {}, new TypeReference<Feed>() {});
 
+    @SuppressWarnings("ImmutableEnumChecker")
     private final TypeToken<?> gsonType;
+    @SuppressWarnings("ImmutableEnumChecker")
     private final TypeReference<?> jacksonType;
 
     private Document(TypeToken<?> typeToken, TypeReference<?> typeReference) {
diff --git a/pom.xml b/pom.xml
index d56e34ce..f1c1946c 100644
--- a/pom.xml
+++ b/pom.xml
@@ -99,7 +99,7 @@
             <compilerArgs>
               <!-- Args related to Error Prone, see: https://errorprone.info/docs/installation#maven -->
               <arg>-XDcompilePolicy=simple</arg>
-              <arg>-Xplugin:ErrorProne -XepExcludedPaths:.*gson/src/test.*|.*extras/src/test.*|.*proto.*</arg>
+              <arg>-Xplugin:ErrorProne -XepExcludedPaths:.*/generated-test-sources/protobuf/.*</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>
@@ -144,6 +144,7 @@
             <detectJavaApiLink>false</detectJavaApiLink>
             <links>
               <link>https://docs.oracle.com/en/java/javase/11/docs/api/</link>
+              <link>https://errorprone.info/api/latest/</link>
             </links>
             <!-- Disable detection of offline links between Maven modules: 
               (1) Only `gson` module is published, so for other modules Javadoc links don't 
diff --git a/proto/src/test/java/com/google/gson/protobuf/functional/ProtosWithAnnotationsTest.java b/proto/src/test/java/com/google/gson/protobuf/functional/ProtosWithAnnotationsTest.java
index 7fb92e89..b9094344 100644
--- a/proto/src/test/java/com/google/gson/protobuf/functional/ProtosWithAnnotationsTest.java
+++ b/proto/src/test/java/com/google/gson/protobuf/functional/ProtosWithAnnotationsTest.java
@@ -28,8 +28,6 @@ import com.google.gson.protobuf.generated.Annotations;
 import com.google.gson.protobuf.generated.Bag.OuterMessage;
 import com.google.gson.protobuf.generated.Bag.ProtoWithAnnotations;
 import com.google.gson.protobuf.generated.Bag.ProtoWithAnnotations.InnerMessage;
-import com.google.gson.protobuf.generated.Bag.ProtoWithAnnotations.InnerMessage.Data;
-import com.google.gson.protobuf.generated.Bag.ProtoWithAnnotations.InnerMessage.Type;
 import com.google.protobuf.GeneratedMessageV3;
 import org.junit.Before;
 import org.junit.Test;
@@ -111,11 +109,11 @@ public class ProtosWithAnnotationsTest {
     assertThat(proto.hasInnerMessage1()).isFalse();
     assertThat(proto.getInnerMessage2()).isEqualTo(InnerMessage.newBuilder()
         .setNIdCt(98798465)
-        .setContent(Type.TEXT)
-        .addData(Data.newBuilder()
+        .setContent(InnerMessage.Type.TEXT)
+        .addData(InnerMessage.Data.newBuilder()
             .setData("OFIN8e9fhwoeh8((⁹8efywoih")
             .setHeight(665))
-        .addData(Data.newBuilder()
+        .addData(InnerMessage.Data.newBuilder()
             .setData("65")
             .setWidth(-56684))
         .build());
@@ -149,7 +147,7 @@ public class ProtosWithAnnotationsTest {
         + "   \"content\":\"UNKNOWN\"%n"
         + "}");
     InnerMessage proto = gson.fromJson(json, InnerMessage.class);
-    assertThat(proto.getContent()).isEqualTo(Type.UNKNOWN);
+    assertThat(proto.getContent()).isEqualTo(InnerMessage.Type.UNKNOWN);
   }
 
   @Test
@@ -171,7 +169,7 @@ public class ProtosWithAnnotationsTest {
         + "   \"content\":\"0\"%n"
         + "}");
     InnerMessage proto = gsonWithEnumNumbers.fromJson(json, InnerMessage.class);
-    assertThat(proto.getContent()).isEqualTo(Type.UNKNOWN);
+    assertThat(proto.getContent()).isEqualTo(InnerMessage.Type.UNKNOWN);
     String rebuilt = gsonWithEnumNumbers.toJson(proto);
     assertThat(rebuilt).isEqualTo("{\"content\":0}");
 
@@ -179,7 +177,7 @@ public class ProtosWithAnnotationsTest {
         + "   \"content\":\"2\"%n"
         + "}");
     proto = gsonWithEnumNumbers.fromJson(json, InnerMessage.class);
-    assertThat(proto.getContent()).isEqualTo(Type.IMAGE);
+    assertThat(proto.getContent()).isEqualTo(InnerMessage.Type.IMAGE);
     rebuilt = gsonWithEnumNumbers.toJson(proto);
     assertThat(rebuilt).isEqualTo("{\"content\":2}");
   }
@@ -194,11 +192,11 @@ public class ProtosWithAnnotationsTest {
             .setLongTimestamp(468406876880768L))
         .setInnerMessage1(InnerMessage.newBuilder()
             .setNIdCt(12)
-            .setContent(Type.IMAGE)
-            .addData(Data.newBuilder()
+            .setContent(InnerMessage.Type.IMAGE)
+            .addData(InnerMessage.Data.newBuilder()
                 .setData("data$$")
                 .setWidth(200))
-            .addData(Data.newBuilder()
+            .addData(InnerMessage.Data.newBuilder()
                 .setHeight(56)))
         .build();
 
diff --git a/proto/src/test/java/com/google/gson/protobuf/functional/ProtosWithPrimitiveTypesTest.java b/proto/src/test/java/com/google/gson/protobuf/functional/ProtosWithPrimitiveTypesTest.java
index 0666a6dd..53f65fe9 100644
--- a/proto/src/test/java/com/google/gson/protobuf/functional/ProtosWithPrimitiveTypesTest.java
+++ b/proto/src/test/java/com/google/gson/protobuf/functional/ProtosWithPrimitiveTypesTest.java
@@ -57,7 +57,6 @@ public class ProtosWithPrimitiveTypesTest {
 
   @Test
   public void testSerializeProto() {
-    Descriptor descriptor = SimpleProto.getDescriptor();
     SimpleProto proto = SimpleProto.newBuilder()
       .setCount(3)
       .setMsg("foo")