code: void markKnownViewsInvalid() {
          final int childCount = getChildCount();
  
          for (int i = 0; i < childCount; i++) {
              final ViewHolder holder = getChildViewHolderInt(getChildAt(i));
              if (holder != null) {
                  holder.addFlags(ViewHolder.FLAG_UPDATE | ViewHolder.FLAG_INVALID);
              }
          }
          mRecycler.markKnownViewsInvalid();
      }
docs: Mark all known views as invalid. Used in response to a, "the whole world might have changed"
  data change event.