Bug 65762 [Viewers] Need to back out of change to AbstractTreeViewer.isExpandable
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/viewsupport/ProblemTreeViewer.java
if (item instanceof Item) {
			fResourceToItemsMapper.addToMap(element, (Item) item);
		}
	}
	/*
	 * @see StructuredViewer#unmapElement(Object, Widget)
	 */
	protected void unmapElement(Object element, Widget item) {
		if (item instanceof Item) {
			fResourceToItemsMapper.removeFromMap(element, (Item) item);
		}		
		super.unmapElement(element, item);
	}
	/*
	 * @see StructuredViewer#unmapAllElements()
	 */
	protected void unmapAllElements() {
		fResourceToItemsMapper.clearMap();
		super.unmapAllElements();
	}
	/*
	 * @see ContentViewer#handleLabelProviderChanged(LabelProviderChangedEvent)
	 */
	protected void handleLabelProviderChanged(LabelProviderChangedEvent event) {
		if (event instanceof ProblemsLabelChangedEvent) {
			ProblemsLabelChangedEvent e= (ProblemsLabelChangedEvent) event;
			if (!e.isMarkerChange() && canIgnoreChangesFromAnnotionModel()) {
				return;
			}
		}