Bug 189636 Custom rule template failing
Null poonter exception being thrown when trying to add a custom rule which is causing the rule cretion to fail. Also there is a minor typo in the rule template string.
bundles/org.eclipse.ui.navigator/src/org/eclipse/ui/internal/navigator/NavigatorContentService.java
private final VisibilityAssistant assistant;
	private NavigatorFilterService navigatorFilterService;
	private INavigatorSorterService navigatorSorterService;
	private INavigatorPipelineService navigatorPipelineService;
	private INavigatorDnDService navigatorDnDService;
	private INavigatorActivationService navigatorActivationService;
	private NavigatorSaveablesService navigatorSaveablesService;
	
	private NavigatorExtensionStateService navigatorExtensionStateService;
	private IDescriptionProvider descriptionProvider;
	private boolean contentProviderInitialized;
	private boolean labelProviderInitialized;
	/**
	 * @param aViewerId
	 *            The viewer id for this content service; normally from the
	 *            <b>org.eclipse.ui.views</b> extension.
	 */
	public NavigatorContentService(String aViewerId) {
		super();
		aViewerId = aViewerId != null ? aViewerId : ""; 
		viewerDescriptor = VIEWER_DESCRIPTOR_REGISTRY
				.getNavigatorViewerDescriptor(aViewerId);
		assistant = new VisibilityAssistant(viewerDescriptor, getActivationService());
		getActivationService().addExtensionActivationListener(this);
	}
	/**
	 * @param aViewerId
	 *            The viewer id for this content service; normally from the
	 *            <b>org.eclipse.ui.views</b> extension.
	 * @param aViewer