JComboBoxへのフォーカス移動がInputVerifierの検証で拒否されたらドロップダウンリスト表示をキャンセルする

class BasicComboPopup2 extends BasicComboPopup {
  private transient MouseListener handler2;

  @Override public void uninstallingUI() {
    super.uninstallingUI();
    handler2 = null;
  }

  // Java 9: protected BasicComboPopup2(JComboBox<Object> combo) {
  protected BasicComboPopup2(JComboBox<?> combo) {
    super(combo);
  }

  @Override protected MouseListener createMouseListener() {
    if (Objects.isNull(handler2)) {
      handler2 = new Handler2();
    }
    return handler2;
  }

  private class Handler2 extends MouseAdapter {
    @Override public void mousePressed(MouseEvent e) {
      if (!SwingUtilities.isLeftMouseButton(e) || !comboBox.isEnabled()) {
        return;
      }
      boolean hasFocus = true;
      if (comboBox.isEditable()) {
        Component comp = comboBox.getEditor().getEditorComponent();
        if (!(comp instanceof JComponent) || ((JComponent) comp).isRequestFocusEnabled()) {
          hasFocus = comp.hasFocus() || comp.requestFocusInWindow();
        }
      } else if (comboBox.isRequestFocusEnabled()) {
        hasFocus = comboBox.hasFocus() || comboBox.requestFocusInWindow();
      }
      Component c = e.getComponent();
      if (!hasFocus && c instanceof AbstractButton) {
        ((AbstractButton) c).getModel().setPressed(false);
      }
      if (hasFocus) {
        togglePopup();
      }
    }

    @Override public void mouseReleased(MouseEvent e) {
      Component source = (Component) e.getSource();
      Dimension size = source.getSize();
      Rectangle bounds = new Rectangle(0, 0, size.width - 1, size.height - 1);
      if (!bounds.contains(e.getPoint())) {
        MouseEvent newEvent = SwingUtilities.convertMouseEvent(e.getComponent(), e, list);
        Point location = newEvent.getPoint();
        Rectangle r = new Rectangle();
        list.computeVisibleRect(r);
        if (r.contains(location)) {
          if (comboBox.getSelectedIndex() == list.getSelectedIndex()) {
            comboBox.getEditor().setItem(list.getSelectedValue());
          }
          comboBox.setSelectedIndex(list.getSelectedIndex());
        }
        comboBox.setPopupVisible(false);
      }
      hasEntered = false;
      stopAutoScrolling();
    }
  }
}