Bug 274236 [CommonNavigator] Incorrect check for existence of item in contribution memory
The check in the NavigatorContentService.rememberContribution() should be containsKey(), not containsValue()
bundles/org.eclipse.ui.navigator/src/org/eclipse/ui/internal/navigator/NavigatorContentService.java
}
	/*
	 * (non-Javadoc)
	 * 
	 * @see java.lang.Object#toString()
	 */
	public String toString() {
		return "ContentService[" + viewerDescriptor.getViewerId() + "]"; 
	}
	private void notifyListeners(NavigatorContentExtension aDescriptorInstance) {
		if (listeners.size() == 0) {
			return;
		}
		INavigatorContentServiceListener listener = null;
		List failedListeners = null;
		for (Iterator listenersItr = listeners.iterator(); listenersItr
				.hasNext();) {
			try {
				listener = (INavigatorContentServiceListener) listenersItr
						.next();
				listener.onLoad(aDescriptorInstance);
			} catch (RuntimeException re) {
				if (failedListeners == null) {
					failedListeners = new ArrayList();
				}
				failedListeners.add(listener);
			}
		}
		if (failedListeners != null) {
			listeners.removeAll(failedListeners);