Bug 305703 [Viewers][CommonNavigator] remembered contributions can leak when using filters
bundles/org.eclipse.ui.navigator/src/org/eclipse/ui/internal/navigator/NavigatorContentService.java
/**
	 * 
	 * The label provider that is are enabled for the given element.
	 * A label provider is 'enabled' if its corresponding content provider
	 * returned the element.
	 * 
	 * @param anElement
	 *            An element from the tree (any element contributed to the
	 *            tree).
	 * @return The label provider
	 */
	public ILabelProvider[] findRelevantLabelProviders(Object anElement) {
		Collection extensions = findPossibleLabelExtensions(anElement);
		
		if (extensions.size() == 0) {
			return NO_LABEL_PROVIDERS;
		}
		List resultProvidersList = new ArrayList();
		for (Iterator itr = extensions.iterator(); itr.hasNext();) {
			resultProvidersList.add(((NavigatorContentExtension) itr.next()).getLabelProvider());
		}
		return (ILabelProvider[]) resultProvidersList.toArray(new ILabelProvider[resultProvidersList.size()]);
	}
	/**
	 * Search for extensions that declare the given element in their
	 * <b>triggerPoints</b> expression.
	 * 
	 * @param anElement
	 *            The element to use in the query