Fix duplicate fields test. The repeated version is passing because null values…

Fix duplicate fields test. The repeated version is passing because null values in a repeated field are rejected and not testing what it wanted to. Also adds a oneof version that verifies the case of oneof fields of different names (currently only same name check seems to be tested).

Also fix spelling of a test.

java/util/src/test/java/com/google/protobuf/util/JsonFormatTest.java

@@ -264,7 +264,7 @@ public class JsonFormatTest extends TestCase {
     assertRoundTripEquals(message);
   }
 
-  public void testParserAcceptStringForNumbericField() throws Exception {
+  public void testParserAcceptStringForNumericField() throws Exception {
     TestAllTypes.Builder builder = TestAllTypes.newBuilder();
     mergeFromJson(
         "{\n"
@@ -479,8 +479,8 @@ public class JsonFormatTest extends TestCase {
       TestAllTypes.Builder builder = TestAllTypes.newBuilder();
       mergeFromJson(
           "{\n"
-              + "  \"repeatedNestedMessage\": [null, null],\n"
-              + "  \"repeated_nested_message\": [null, null]\n"
+              + "  \"repeatedInt32\": [1, 2],\n"
+              + "  \"repeated_int32\": [5, 6]\n"
               + "}",
           builder);
       fail();
@@ -488,7 +488,7 @@ public class JsonFormatTest extends TestCase {
       // Exception expected.
     }
 
-    // Duplicated oneof fields.
+    // Duplicated oneof fields, same name.
     try {
       TestOneof.Builder builder = TestOneof.newBuilder();
       mergeFromJson("{\n" + "  \"oneofInt32\": 1,\n" + "  \"oneof_int32\": 2\n" + "}", builder);
@@ -496,6 +496,16 @@ public class JsonFormatTest extends TestCase {
     } catch (InvalidProtocolBufferException e) {
       // Exception expected.
     }
+
+    // Duplicated oneof fields, different name.
+    try {
+      TestOneof.Builder builder = TestOneof.newBuilder();
+      mergeFromJson(
+          "{\n" + "  \"oneofInt32\": 1,\n" + "  \"oneofNullValue\": null\n" + "}", builder);
+      fail();
+    } catch (InvalidProtocolBufferException e) {
+      // Exception expected.
+    }
   }
 
   public void testMapFields() throws Exception {