code: @Override
      int guessPayloadLength() {
          int length = 0;
          byte[] payload = getDataFromPayload();
          if (payload != null) {
              length = payload.length + 24;
          }
          return length;
      }
docs: Provide an estimate of encoded length of the payload
  
  If we have a real object and no serialized one then we have no idea how big it is,
  so leave the guess at 0