TableRowSorterのSortKeysをクリアする

table.setAutoCreateRowSorter(true);
table.getTableHeader().addMouseListener(new MouseAdapter() {
  @Override public void mouseClicked(MouseEvent e) {
    final RowSorter<? extends TableModel> sorter = table.getRowSorter();
    if (sorter == null || sorter.getSortKeys().isEmpty()) {
      return;
    }
    JTableHeader h = (JTableHeader) e.getComponent();
    TableColumnModel columnModel = h.getColumnModel();
    int viewColumn = columnModel.getColumnIndexAtX(e.getX());
    if (viewColumn < 0) {
      return;
    }
    int column = columnModel.getColumn(viewColumn).getModelIndex();
    if (column != -1 && e.isShiftDown()) {
      EventQueue.invokeLater(new Runnable() {
        @Override public void run() {
          sorter.setSortKeys(null);
        }
      });
    }
  }
});