Adds getters for config fields.

This adds simple getters for certain config fields that would be helpful in custom
TypeAdapters to deal with situations like this:
https://github.com/rharter/auto-value-gson/issues/18

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

@@ -127,6 +127,8 @@ public final class Gson {
   private final List<TypeAdapterFactory> factories;
   private final ConstructorConstructor constructorConstructor;
 
+  private final Excluder excluder;
+  private final FieldNamingStrategy fieldNamingStrategy;
   private final boolean serializeNulls;
   private final boolean htmlSafe;
   private final boolean generateNonExecutableJson;
@@ -175,13 +177,15 @@ public final class Gson {
         LongSerializationPolicy.DEFAULT, Collections.<TypeAdapterFactory>emptyList());
   }
 
-  Gson(final Excluder excluder, final FieldNamingStrategy fieldNamingPolicy,
+  Gson(final Excluder excluder, final FieldNamingStrategy fieldNamingStrategy,
       final Map<Type, InstanceCreator<?>> instanceCreators, boolean serializeNulls,
       boolean complexMapKeySerialization, boolean generateNonExecutableGson, boolean htmlSafe,
       boolean prettyPrinting, boolean lenient, boolean serializeSpecialFloatingPointValues,
       LongSerializationPolicy longSerializationPolicy,
       List<TypeAdapterFactory> typeAdapterFactories) {
     this.constructorConstructor = new ConstructorConstructor(instanceCreators);
+    this.excluder = excluder;
+    this.fieldNamingStrategy = fieldNamingStrategy;
     this.serializeNulls = serializeNulls;
     this.generateNonExecutableJson = generateNonExecutableGson;
     this.htmlSafe = htmlSafe;
@@ -244,11 +248,27 @@ public final class Gson {
     factories.add(new JsonAdapterAnnotationTypeAdapterFactory(constructorConstructor));
     factories.add(TypeAdapters.ENUM_FACTORY);
     factories.add(new ReflectiveTypeAdapterFactory(
-        constructorConstructor, fieldNamingPolicy, excluder));
+        constructorConstructor, fieldNamingStrategy, excluder));
 
     this.factories = Collections.unmodifiableList(factories);
   }
 
+  public Excluder excluder() {
+    return excluder;
+  }
+
+  public FieldNamingStrategy fieldNamingStrategy() {
+    return fieldNamingStrategy;
+  }
+
+  public boolean serializeNulls() {
+    return serializeNulls;
+  }
+
+  public boolean htmlSafe() {
+    return htmlSafe;
+  }
+
   private TypeAdapter<Number> doubleAdapter(boolean serializeSpecialFloatingPointValues) {
     if (serializeSpecialFloatingPointValues) {
       return TypeAdapters.DOUBLE;

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

@@ -0,0 +1,54 @@
+/*
+ * Copyright (C) 2016 The Gson Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.gson;
+
+import com.google.gson.internal.Excluder;
+import java.lang.reflect.Field;
+import java.lang.reflect.Type;
+import java.util.ArrayList;
+import java.util.HashMap;
+import junit.framework.TestCase;
+
+/**
+ * Unit tests for {@link Gson}.
+ *
+ * @author Ryan Harter
+ */
+public final class GsonTest extends TestCase {
+
+  private static final Excluder CUSTOM_EXCLUDER = Excluder.DEFAULT
+      .excludeFieldsWithoutExposeAnnotation()
+      .disableInnerClassSerialization();
+
+  private static final FieldNamingStrategy CUSTOM_FIELD_NAMING_STRATEGY = new FieldNamingStrategy() {
+    @Override public String translateName(Field f) {
+      return "foo";
+    }
+  };
+
+  public void testOverridesDefaultExcluder() {
+    Gson gson = new Gson(CUSTOM_EXCLUDER, CUSTOM_FIELD_NAMING_STRATEGY,
+        new HashMap<Type, InstanceCreator<?>>(), true, false, true, false,
+        true, true, false, LongSerializationPolicy.DEFAULT,
+        new ArrayList<TypeAdapterFactory>());
+
+    assertEquals(CUSTOM_EXCLUDER, gson.excluder());
+    assertEquals(CUSTOM_FIELD_NAMING_STRATEGY, gson.fieldNamingStrategy());
+    assertEquals(true, gson.serializeNulls());
+    assertEquals(false, gson.htmlSafe());
+  }
+}