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/extensions/StructuredViewerManager.java
private StructuredViewer viewer;
	private Object cachedOldInput;
	private Object cachedNewInput;
	/*
	 * This map is used to associate elements in the viewer with their
	 * associated NavigatorContentDescriptor. To avoid things getting out of
	 * hand, it associates only the items that are actually present in the tree.
	 * We need this association to make sure that we can always get the source
	 * (NavigatorContentDescriptor) of a given element for the case of providing
	 * the label which must use the same navigator content extension that
	 * provided the element.
	 */
	
	private Map viewerDataMap;
	
	static class StructuredViewerAccess extends StructuredViewerInternals {
		static class Listener implements StructuredViewerInternals.AssociateListener {
			private final NavigatorContentService contentService;
			private final Map viewerDataMap;
			public Listener(NavigatorContentService contentService, Map viewerDataMap) {
				this.contentService = contentService;