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