JComboBoxのArrowButtonを隠す

Object[] items = {"JComboBox 11111:", "JComboBox 222:", "JComboBox 33:"};
UIManager.put("ComboBox.squareButton", Boolean.FALSE);
JComboBox comboBox = new JComboBox(items);
comboBox.setUI(new BasicComboBoxUI() {
  @Override protected JButton createArrowButton() {
    JButton button = new JButton(); //super.createArrowButton();
    button.setBorder(BorderFactory.createEmptyBorder());
    button.setVisible(false);
    return button;
  }
});
comboBox.setOpaque(true);
comboBox.setBackground(p.getBackground());
comboBox.setBorder(BorderFactory.createEmptyBorder(0, 2, 0, 2));
comboBox.setFocusable(false);

UIManager.put("ComboBox.squareButton", Boolean.TRUE);