code: public void updateProgress(int progress, Bundle extraData) {
      if (mReceiver != null) {
        Bundle resultData = new Bundle();
        resultData.putInt(Groundy.PROGRESS, progress);
        resultData.putSerializable(Groundy.TASK_IMPLEMENTATION, getClass());
        if (extraData != null) resultData.putAll(extraData);
        send(OnProgress.class, resultData);
      }
    }
docs: Prepare and sends a progress update to the current receiver. Callback used is {@link
  com.telly.groundy.annotations.OnProgress} and it will contain a bundle with an integer extra
  called {@link Groundy#PROGRESS}
  
  @param extraData additional information to send to the progress callback
  @param progress percentage to send to receiver