codigo para poner un botón transparente en java

mport javax.swing.*;
import java.awt.*;
import java.awt.event.*;

public class Test extends JFrame {

    private JPanel contentPane;
    private JButton button;

    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                try {
                    Test frame = new Test();