@Override
          public void toggleSortOrder(int column) {
            if (isSortable(column)) {
              SortKey oldKey = ContainerUtil.getFirstItem(getSortKeys());
              SortOrder oldOrder;
              if (oldKey == null || oldKey.getColumn() != column) {
                oldOrder = SortOrder.UNSORTED;
              }
              else {
                oldOrder = oldKey.getSortOrder();
              }
              setSortKeys(Collections.singletonList(new SortKey(column, getNextSortOrder(oldOrder))));
            }
          }
@Override
          public void toggleSortOrder(int column)