docs: private VS createViewState() {
      VS viewState = delegateCallback.createViewState();
      if (viewState == null) {
        throw new NullPointerException(
            "ViewState returned from createViewState() is null. Fragment is " + fragment);
      }
  
      if (keepPresenterInstanceDuringScreenOrientationChanges) {
        PresenterManager.putViewState(getActivity(), mosbyViewId, viewState);
      }
  
      return viewState;
    }