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
*            An array of elements from the given source.
	 */
	public synchronized void rememberContribution(
			NavigatorContentDescriptor source, Object[] elements) {
		if (source != null && elements != null) {
			for (int i = 0; i < elements.length; i++) {
				getContributionMemory().put(elements[i], source);
			}
		}
	}
	/**
	 * Remember that the elements in the given array came from the given source
	 * 
	 * @param source
	 *            The descriptor of the extension that contributed the set of
	 *            elements.
	 * @param element
	 *            An element from the given source.
	 */
	public synchronized void rememberContribution(
			NavigatorContentDescriptor source, Object element) {
		if (source != null && element != null) {
			getContributionMemory().put(element, source);
		}
	}
	/**
	 * 
	 * @param element
	 *            The element contributed by the descriptor to be returned
	 * @return The descriptor that contributed the element or null.