MouseEvent getModifiersEx() call does not work as expected (or as documented)

I have some classes needing to migrate from the old deprecated call: MouseEvent getModifiers()

That need to be converted to the new style: MouseEvent getModifiersEx()

Clicking on the frame in the example calls the mouse listener. Note that the (deprecated) getModifiers() gives the expected results for rt-click vs lt-click:

 right click: 4, left click: 16

This shows that rt-click is distinguishable from lt-click and the bit values are as expected.

However, using getModifiersEx() does not show the expected values.

The expected bit values for getModifiersEx are:

 right click: 4096, left click: 1024

But the actual values seen are:

 right click: 0, left click: 0

This makes rt-click vs lt-click indistinguishable.

Note that pressing the modifier keys (e.g. Shift, Cntrl, Alt) does set the expected bits (but the button down mask bits are still zero so rt-click vs lt-click are still indistinguishable)

Calling MouseEvent getButton() does return the correct button, so that is a work-around. But why does getModifiersEx() not work?

This is on MacOS BTW

/**Example showing issue with MouseEvent.getModifiersEx()*/
public class TrialGetModEx extends JFrame {

  public TrialGetModEx() {
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    setSize(300, 200);
    setLocation(100,100);
    setVisible(true);

    addMouseListener(new MouseAdapter() {
      public void mouseClicked(MouseEvent e) {
        System.out.print("Mod="+e.getModifiers());
        System.out.print(" ModEx="+e.getModifiersEx());
        System.out.println();
      }

    });

    System.out.println("Expected Bit values:");
    System.out.println("  BUTTON_1_MASK: "+MouseEvent.BUTTON1_MASK);
    System.out.println("  BUTTON_3_MASK: "+MouseEvent.BUTTON3_MASK);
    System.out.println("  BUTTON_1_DOWN_MASK: "+MouseEvent.BUTTON1_DOWN_MASK);
    System.out.println("  BUTTON_3_DOWN_MASK: "+MouseEvent.BUTTON3_DOWN_MASK);
  }

  public static void main(String[] args) {
    new TrialGetModEx();
  }
}