docs: public boolean contains(MappeableContainer subset) {
      if(subset instanceof MappeableRunContainer) {
        return contains((MappeableRunContainer)subset);
      } else if(subset instanceof MappeableArrayContainer) {
        return contains((MappeableArrayContainer) subset);
      } else if(subset instanceof MappeableBitmapContainer){
        return contains((MappeableBitmapContainer)subset);
      }
      return false;
    }