JTableのソートアイコンを変更

class EmptyIcon implements Icon {
  @Override public void paintIcon(Component c, Graphics g, int x, int y) {
    /* Empty icon */
  }

  @Override public int getIconWidth() {
    return 0;
  }

  @Override public int getIconHeight() {
    return 0;
  }
}
// ...
UIManager.put("Table.ascendingSortIcon", new IconUIResource(new EmptyIcon()));
UIManager.put("Table.descendingSortIcon", new IconUIResource(new EmptyIcon()));