code: public void onSaveInstanceState(Bundle bundle) {
      bundle.putParcelableArrayList(TASK_PROXY_LIST, proxyTasks);
      for (TaskHandler proxyTask : proxyTasks) {
        bundle.putParcelable(GROUNDY_PROXY_KEY_PREFIX + proxyTask.getTaskId(), proxyTask);
      }
    }
docs: Saves the current callback handlers information in order to restore them after the
  configuration change.
  
  @param bundle the same bundle you receive from within your activity or fragment
  onSaveInstanceState method