code: public static void merge(CharSequence input,
                               ExtensionRegistry extensionRegistry,
                               Message.Builder builder) throws ParseException {
          Tokenizer tokenizer = new Tokenizer(input);
  
          // Based on the state machine @ http://json.org/
  
          tokenizer.consume("{"); // Needs to happen when the object starts.
          while (!tokenizer.tryConsume("}")) { // Continue till the object is done
              mergeField(tokenizer, extensionRegistry, builder);
          }
      }
docs: Parse a text-format message from {@code input} and merge the contents into {@code builder}.
  Extensions will be recognized if they are registered in {@code extensionRegistry}.