java.util.ConcurrentModificationException

[ducciovigolo]

Hi Kim,
i receive this error
java.util.ConcurrentModificationException
at java.util.ArrayList$Itr.checkForComodification(ArrayList.java:859)
at java.util.ArrayList$Itr.next(ArrayList.java:831)
at org.vaadin.kim.countdownclock.CountdownClock$1.countdownEnded(CountdownClock.java:30)
when I invoke removeEndEventListener from the EndEventListener.countDownEnded method, like this:

    private final EndEventListener endEventListener = new EndEventListener() {
        @Override
        public void countDownEnded(CountdownClock clock) {
            clock.removeEndEventListener(this);
        }
    };