@Override
    public void printStackTrace(PrintStream ps) {
        super.printStackTrace(ps);
        if (nestedThrowable != null) {
            nestedThrowable.printStackTrace(ps);
        }
    }
Thrown when User cannot be found.

@author Iain Shigeoka
xmppserver/src/main/java/org/jivesoftware/openfire/user/UserNotFoundException.java