code: @UiThread
      public void notifyParentChanged(int parentPosition) {
          P parent = mParentList.get(parentPosition);
          int flatParentPositionStart = getFlatParentPosition(parentPosition);
          int sizeChanged = changeParentWrapper(flatParentPositionStart, parent);
  
          notifyItemRangeChanged(flatParentPositionStart, sizeChanged);
      }
docs: Notify any registered observers that the parent at {@code parentPosition} has changed.
  This will also trigger an item changed for children of the parent list specified.
  <p>
  This is an item change event, not a structural change event. It indicates that any
  reflection of the data at {@code parentPosition} is out of date and should be updated.
  The parent at {@code parentPosition} retains the same identity. This means
  the number of children must stay the same.
  
  @param parentPosition Position of the item that has changed