Bug 19014 Empty CU after reorg
F2 - enable single click and show in members in packages view - open TestCase.java in editor - give focus to packages view - change it on disk - copy a method in TestCase using DnD - activate the TestCase.java editor - answer question with no - activate revert from context menu observe: CU is empty
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/javaeditor/CompilationUnitDocumentProvider.java
*/
			public boolean hasOverlay() {
				return false;
			}
			
			/*
			 * @see IProblemAnnotation#addOverlaid(IProblemAnnotation)
			 */
			public void addOverlaid(IProblemAnnotation annotation) {
				if (fOverlaids == null)
					fOverlaids= new ArrayList(1);
				fOverlaids.add(annotation);
			}
			/*
			 * @see IProblemAnnotation#removeOverlaid(IProblemAnnotation)
			 */
			public void removeOverlaid(IProblemAnnotation annotation) {
				if (fOverlaids != null) {
					fOverlaids.remove(annotation);
					if (fOverlaids.size() == 0)
						fOverlaids= null;
				}
			}
			
			/*
			 * @see IProblemAnnotation#getOverlaidIterator()
			 */
			public Iterator getOverlaidIterator() {
				if (fOverlaids != null)
					return fOverlaids.iterator();