Bug 275929 [CommonNavigator] IPipelinedTreeContentProvider.getPipelinedElements() not ever called
bundles/org.eclipse.ui.navigator/src/org/eclipse/ui/internal/navigator/NavigatorContentServiceContentProvider.java
* @param aParentElement
	 *            An element that requires children content in the viewer (e.g.
	 *            an end-user expanded a node)
	 * @return A non-null array of objects that are logical children of
	 *         aParentElement
	 * @see org.eclipse.jface.viewers.ITreeContentProvider#getChildren(java.lang.Object)
	 */
	public synchronized Object[] getChildren(Object aParentElement) {	
		return internalGetChildren(aParentElement);
	}
	private Object[] internalGetChildren(Object aParentElementOrPath) {
		contentService.resetContributionMemory();
		Object aParentElement = internalAsElement(aParentElementOrPath);
		Set enabledExtensions = contentService
				.findContentExtensionsByTriggerPoint(aParentElement);
		if (enabledExtensions.size() == 0) {
			return NO_CHILDREN;
		}
		ContributorTrackingSet finalChildrenSet = new ContributorTrackingSet(contentService);
		ContributorTrackingSet localSet = new ContributorTrackingSet(contentService);
		Object[] contributedChildren = null;
		NavigatorContentExtension foundExtension;
		NavigatorContentExtension[] overridingExtensions;
		for (Iterator itr = enabledExtensions.iterator(); itr.hasNext();) {
			foundExtension = (NavigatorContentExtension) itr.next();
			try {
				if (!isOverridingExtensionInSet(foundExtension.getDescriptor(),
						enabledExtensions)) {
					contributedChildren = foundExtension.internalGetContentProvider()
							.getChildren(aParentElementOrPath);