Bug 275929 [CommonNavigator] IPipelinedTreeContentProvider.getPipelinedElements() not ever called
bundles/org.eclipse.ui.navigator/src/org/eclipse/ui/internal/navigator/NavigatorContentServiceContentProvider.java
* the viewerId supplied when the {@link NavigatorContentService}&nbsp; was
	 * created (either by this class or its client). The extensions will then be
	 * queried for relevant content. The children returned from each extension
	 * will be aggregated and returned as is -- there is no additional sorting
	 * or filtering at this level.
	 * </p>
	 * <p>
	 * The results of this method will be displayed in the root of the
	 * TreeViewer.
	 * </p>
	 * {@inheritDoc}
	 * 
	 * @param anInputElement
	 *            The relevant element that a client would like children for -
	 *            the input element of the TreeViewer
	 * @return A non-null array of objects that are logical children of
	 *         anInputElement
	 * @see org.eclipse.jface.viewers.IStructuredContentProvider#getElements(java.lang.Object)
	 */
	public synchronized Object[] getElements(Object anInputElement) {
		contentService.resetContributionMemory();
		Set rootContentExtensions = contentService
				.findRootContentExtensions(anInputElement);
		if (rootContentExtensions.size() == 0) {
			return NO_CHILDREN;
		}
		ContributorTrackingSet finalElementsSet = new ContributorTrackingSet(contentService);
		ContributorTrackingSet localSet = new ContributorTrackingSet(contentService);		
		Object[] contributedChildren = null;
		NavigatorContentExtension foundExtension;