Bug 305703 [Viewers][CommonNavigator] remembered contributions can leak when using filters
bundles/org.eclipse.ui.navigator/src/org/eclipse/ui/internal/navigator/NavigatorContentService.java
synchronized (this) {
			for (Iterator contentItr = contentExtensions.values().iterator(); contentItr
					.hasNext();) {
				((NavigatorContentExtension) contentItr.next()).dispose();
			}
		}
		getActivationService().removeExtensionActivationListener(this);
		assistant.dispose();
		isDisposed = true;
	}
	protected void updateService(Viewer aViewer, Object anOldInput,
			Object aNewInput) {
		
		
		
		if (isDisposed)
			return;
		synchronized (this) {
			if (structuredViewerManager == null) {
				structuredViewerManager = new StructuredViewerManager((StructuredViewer) aViewer, this);
				structuredViewerManager.inputChanged(anOldInput, aNewInput);
			} else {
				structuredViewerManager.inputChanged(aViewer, anOldInput,
						aNewInput);
			}
			for (Iterator contentItr = contentExtensions.values().iterator(); contentItr
					.hasNext();) {
				NavigatorContentExtension ext = (NavigatorContentExtension) contentItr
						.next();
				if (ext.isLoaded()) {