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
if (structuredViewerManager != null) {
			structuredViewerManager.safeRefresh();
		}
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.ui.internal.navigator.INavigatorContentService#getViewerId()
	 */
	public final String getViewerId() {
		return viewerDescriptor.getViewerId();
	}
	/**
	 * 
	 * @param aDescriptorKey
	 *            A descriptor
	 * @return The cached NavigatorContentExtension from the descriptor
	 */
	public final NavigatorContentExtension getExtension(
			INavigatorContentDescriptor aDescriptorKey) {
		return getExtension(aDescriptorKey, true);
	}
	/**
	 * 
	 * @param aDescriptorKey
	 * @param toLoadIfNecessary
	 *            True if the extension should be loaded if it is not already.
	 * @return The instance of the extension for the given descriptor key.
	 */
	public final NavigatorContentExtension getExtension(