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
INavigatorContentExtension ext = getExtension(desc);
		if (ext == null) {
			return null;
		}
		return ext.getStateModel();
	}
	/**
	 * Return a set of content providers that could provide a parent for the
	 * given element. These content extensions are determined by consulting the
	 * <b>possibleChildren</b> expression in the <b>navigatorContent</b>
	 * extension.
	 * 
	 * <p>
	 * Clients that wish to tap into the link with editor support must describe
	 * all of their possible children in their <b>possibleChildren</b>
	 * expressions.
	 * </p>
	 * 
	 * @param anElement
	 *            An element from the tree (generally from a setSelection()
	 *            method).
	 * @return The set of content providers that may be able to provide a
	 *         parent.
	 */
	public ITreeContentProvider[] findParentContentProviders(Object anElement) {
		return extractContentProviders(findContentExtensionsWithPossibleChild(anElement));
	}
	/**
	 * <p>
	 * Return all of the content providers that are relevant for the viewer. The