Bug 299438 [CommonNavigator] CNF viewer state non properly reset when NCEs are activated or deactivated
The map of the objects to the NCEs should be reset whenever the NCEs associated with the viewer to change to avoid having stale label information. This has shown up when looking at the CNF tests that change the viewer.
bundles/org.eclipse.ui.navigator/src/org/eclipse/ui/internal/navigator/NavigatorContentService.java
return null;
		}
		INavigatorContentExtension ext = getExtension(desc);
		if (ext == null) {
			return null;
		}
		return ext.getStateModel();
	}
	/**
	 * <p>
	 * Return all of the content providers that are relevant for the viewer. The
	 * viewer is determined by the ID used to create the
	 * INavigatorContentService ({@link #getViewerId() }). See
	 * {@link #createCommonContentProvider() } for more information about how
	 * content providers are located for the root of the viewer. The root
	 * content providers are calculated once. If a new element is supplied, a
	 * client must call {@link #update() } prior in order to reset the calculated
	 * root providers.
	 * </p>
	 * 
	 * @param anElement
	 *            An element from the tree (generally the input of the viewer)
	 * @return The set of content providers that can provide root elements for a
	 *         viewer.
	 */
	public ITreeContentProvider[] findRootContentProviders(Object anElement) {
		if (rootContentProviders != null) {
			return rootContentProviders;
		}
		synchronized (this) {