Clean up warnings.

gson/src/main/java/com/google/gson/FieldNamingStrategy2Adapter.java

@@ -31,8 +31,7 @@ final class FieldNamingStrategy2Adapter implements FieldNamingStrategy2 {
     Preconditions.checkNotNull(adaptee);
     this.adaptee = adaptee;
   }
-  
-  @SuppressWarnings("deprecation")
+
   public String translateName(FieldAttributes f) {
     return adaptee.translateName(f.getFieldObject());
   }

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

@@ -218,12 +218,9 @@ public final class Gson {
    * @since 1.4
    */
   public JsonElement toJsonTree(Object src, Type typeOfSrc) {
-    if (src == null) {
-      return JsonNull.createJsonNull();
-    }
     JsonSerializationContextDefault context = new JsonSerializationContextDefault(
         createDefaultObjectNavigatorFactory(serializationExclusionStrategy), serializeNulls, serializers);
-    return context.serialize(src, typeOfSrc, true);
+    return context.serialize(src, typeOfSrc);
   }
 
   /**

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

@@ -46,10 +46,13 @@ final class JsonSerializationContextDefault implements JsonSerializationContext
   }
 
   public JsonElement serialize(Object src, Type typeOfSrc) {
+    if (src == null) {
+      return JsonNull.createJsonNull();
+    }
     return serialize(src, typeOfSrc, true);
   }
 
-  public JsonElement serialize(Object src, Type typeOfSrc, boolean preserveType) {
+  JsonElement serialize(Object src, Type typeOfSrc, boolean preserveType) {
     ObjectNavigator on = factory.create(new ObjectTypePair(src, typeOfSrc, preserveType));
     JsonSerializationVisitor visitor =
         new JsonSerializationVisitor(factory, serializeNulls, serializers, this, ancestors);

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

@@ -30,8 +30,9 @@ package com.google.gson;
  * @author Joel Leitch
  */
 final class Preconditions {
-  public static void checkNotNull(Object obj) {
+  public static <T> T checkNotNull(T obj) {
     checkArgument(obj != null);
+    return obj;
   }
 
   public static void checkArgument(boolean condition) {

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

@@ -421,7 +421,7 @@ public final class Types {
    * Returns the declaring class of {@code typeVariable}, or {@code null} if it was not declared by
    * a class.
    */
-  @SuppressWarnings({ "rawtypes", "unchecked" })
+  @SuppressWarnings("unchecked")
   private static Class<?> declaringClassOf(TypeVariable typeVariable) {
     GenericDeclaration genericDeclaration = typeVariable.getGenericDeclaration();
     return genericDeclaration instanceof Class
@@ -438,7 +438,7 @@ public final class Types {
     private final Type rawType;
     private final Type[] typeArguments;
 
-    @SuppressWarnings({ "rawtypes", "unchecked" })
+    @SuppressWarnings("unchecked")
     public ParameterizedTypeImpl(Type ownerType, Type rawType, Type... typeArguments) {
       // require an owner type if the raw type needs it
       if (rawType instanceof Class<?>) {

gson/src/test/java/com/google/gson/functional/PrintFormattingTest.java

@@ -45,7 +45,7 @@ public class PrintFormattingTest extends TestCase {
     gson = new Gson();
   }
 
-  @SuppressWarnings({ "unchecked", "rawtypes" })
+  @SuppressWarnings("unchecked")
   public void testCompactFormattingLeavesNoWhiteSpace() {
     List list = new ArrayList();
     list.add(new BagOfPrimitives());