Only for Nimbus LAF UIManager.get("PasswordField.echoChar") is null

FULL PRODUCT VERSION :
J2SE 1.6.0_13

ADDITIONAL OS VERSION INFORMATION :
Windows Vista SP1 PL

A DESCRIPTION OF THE PROBLEM :
I'm using UIManager.get("PasswordField.echoChar") to get the default echo char. I need this default char to allow user to show and hide password.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Character DEFAULT_ECHO_CHARACTER = (Character) javax.swing.UIManager.get("PasswordField.echoChar");

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
DEFAULT_ECHO_CHARACTER != null
ACTUAL -
DEFAULT_ECHO_CHARACTER == null

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
    public static void main(String[] args) {
        try {
            javax.swing.UIManager.setLookAndFeel("com.sun.java.swing.plaf.windows.WindowsLookAndFeel");
            System.out.println("Echo char in WindowsLookAndFeel: " + javax.swing.UIManager.get("PasswordField.echoChar"));

            javax.swing.UIManager.setLookAndFeel("com.sun.java.swing.plaf.windows.WindowsClassicLookAndFeel");
            System.out.println("Echo char in WindowsClassicLookAndFeel: " + javax.swing.UIManager.get("PasswordField.echoChar"));

            javax.swing.UIManager.setLookAndFeel("com.sun.java.swing.plaf.motif.MotifLookAndFeel");
            System.out.println("Echo char in MotifLookAndFeel: " + javax.swing.UIManager.get("PasswordField.echoChar"));

            javax.swing.UIManager.setLookAndFeel("javax.swing.plaf.metal.MetalLookAndFeel");
            System.out.println("Echo char in MetalLookAndFeel: " + javax.swing.UIManager.get("PasswordField.echoChar"));

            javax.swing.UIManager.setLookAndFeel("com.sun.java.swing.plaf.nimbus.NimbusLookAndFeel");
            System.out.println("Echo char in NimbusLookAndFeel: " + javax.swing.UIManager.get("PasswordField.echoChar"));
        } catch (Exception ex) {
            ex.printStackTrace();
        }
    }

---------- END SOURCE ----------