code: public static Unauthorized of(int errorCode, String message) {
          touchPayload().errorCode(errorCode).message(message);
          return _INSTANCE;
      }
docs: Returns a static Unauthorized instance and set the {@link #payload} thread local with
  error code and message.
  
  @param errorCode the error code
  @param message the error message
  @return a static Unauthorized instance as described above