Fix quote escaping in JsonFormat.print() for FieldMasks.

#24083

PiperOrigin-RevId: 824592626

Author: alin04

java/util/src/main/java/com/google/protobuf/util/JsonFormat.java

@@ -932,7 +932,7 @@ private void printDuration(MessageOrBuilder message) throws IOException {
     /** Prints google.protobuf.FieldMask */
     private void printFieldMask(MessageOrBuilder message) throws IOException {
       FieldMask value = FieldMask.parseFrom(toByteString(message));
-      generator.print("\"" + FieldMaskUtil.toJsonString(value) + "\"");
+      generator.print(gson.toJson(FieldMaskUtil.toJsonString(value)));
     }
 
     /** Prints google.protobuf.Struct */

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

@@ -947,6 +947,18 @@ public void testFieldMask() throws Exception {
     assertRoundTripEquals(message);
   }
 
+  @Test
+  public void testFieldMaskWithQuote() throws Exception {
+    TestFieldMask message =
+        TestFieldMask.newBuilder()
+            .setFieldMaskValue(FieldMaskUtil.fromString("foo.bar,baz,foo_bar.baz,\""))
+            .build();
+
+    assertThat(toJsonString(message))
+        .isEqualTo("{\n" + "  \"fieldMaskValue\": \"foo.bar,baz,fooBar.baz,\\\"\"\n" + "}");
+    assertRoundTripEquals(message);
+  }
+
   @Test
   public void testStruct() throws Exception {
     // Build a struct with all possible values.