code: public final void notifyContentItemMoved(int fromPosition, int toPosition) {
          if (fromPosition < 0 || toPosition < 0 || fromPosition >= contentItemCount || toPosition >= contentItemCount) {
              throw new IndexOutOfBoundsException("The given fromPosition " + fromPosition + " or toPosition "
                      + toPosition + " is not within the position bounds for content items [0 - " + (contentItemCount - 1) + "].");
          }
          notifyItemMoved(fromPosition + headerItemCount, toPosition + headerItemCount);
      }
docs: Notifies that an existing content item is moved to another position.
  
  @param fromPosition the original position.
  @param toPosition   the new position.