Bug 275929 [CommonNavigator] IPipelinedTreeContentProvider.getPipelinedElements() not ever called
bundles/org.eclipse.ui.navigator/src/org/eclipse/ui/internal/navigator/NavigatorContentServiceContentProvider.java
INavigatorViewerDescriptor vDesc = contentService.getViewerDescriptor();
		enforceHasChildren = vDesc.getBooleanConfigProperty(NavigatorViewerDescriptor.PROP_ENFORCE_HAS_CHILDREN);
		isContentServiceSelfManaged = true;
	}
	/**
	 * <p>
	 * Uses the supplied content service to acquire the available extensions.
	 * </p>
	 * 
	 * @param aContentService
	 *            The associated NavigatorContentService that should be used to
	 *            acquire information.
	 */
	public NavigatorContentServiceContentProvider(
			NavigatorContentService aContentService) {
		super();
		contentService = aContentService;
		isContentServiceSelfManaged = false;
		INavigatorViewerDescriptor vDesc = contentService.getViewerDescriptor();
		enforceHasChildren = vDesc.getBooleanConfigProperty(NavigatorViewerDescriptor.PROP_ENFORCE_HAS_CHILDREN);
	}
	/**
	 * 
	 * <p>
	 * Return the root objects for the supplied anInputElement. anInputElement
	 * is the root thing that the viewer visualizes.
	 * </p>
	 * <p>
	 * This method will call out to its {@link NavigatorContentService}&nbsp;for
	 * extensions that are enabled on the supplied anInputElement or enabled on