SwingBuilderでコンボボックスに画像とラベルを表示する

SwingBuilderでコンボボックスに画像とラベルを表示するには、以下のコードのようにDefaultListCellRendererのgetListCellRendererComponentメソッドをオーバーライドします。
サンプルコード

import java.awt.*
import javax.swing.*
import groovy.swing.*

class MyItem
{
  def label
  def icon
  public MyItem(label, icon)
  {
    this.label = label
    this.icon = icon
  }
  @Override
  public String toString()
  {
    return label
  }
}

sb = new SwingBuilder()
sb.edt {
  frame(
    title: "example - labels and images in Combobox",
    show: true,
    resizable: true,
    size: [200, 200],
    defaultCloseOperation: WindowConstants.EXIT_ON_CLOSE
  ){
    def options = [
      new MyItem("home", imageIcon(file:"e:/icons/home.png")),
      new MyItem("plane", imageIcon(file:"e:/icons/plane.png")),
      new MyItem("mobile", imageIcon(file:"e:/icons/mobile2.png"))
    ]
    comboBox(id:"cb1", items: options,
      constraints: BorderLayout.NORTH,
      renderer: new DefaultListCellRenderer(){
        @Override
        public Component getListCellRendererComponent(
          JList list, Object value, int index,
          boolean isSelected, boolean cellHasFocus)
        {
          super.getListCellRendererComponent(list, value, index,
            isSelected, cellHasFocus
          )
          if( value instanceof MyItem ){
            setText(value.label)
            setIcon(value.icon)
          }
          return this
        }
      }
    )
    button(text:"OK", constraints: BorderLayout.SOUTH,
      actionPerformed: {
        sb.optionPane(
          message:"combobox1=${sb.cb1.selectedItem}, index=${sb.cb1.selectedIndex}",
          messageType:JOptionPane.INFORMATION_MESSAGE)
          .createDialog("combobox").visible = true
      }
    )
  }

}

実行時画面

動作環境
groovy 2.2.2, JDK 1.7 update55