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
super.removeAllAnnotations(fireModelChanged);
				fReverseMap.clear();
			}
			
			/*
			 * @see AnnotationModel#removeAnnotation(Annotation, boolean)
			 */
			protected void removeAnnotation(Annotation annotation, boolean fireModelChanged) {
				Position position= getPosition(annotation);
				Object cached= fReverseMap.get(position);
				if (cached instanceof List) {
					List list= (List) cached;
					list.remove(annotation);
					if (list.size() == 1) {
						fReverseMap.put(position, list.get(0));
						list.clear();
					}
				} else if (cached instanceof Annotation) {
					fReverseMap.remove(position);
				}
				
				super.removeAnnotation(annotation, fireModelChanged);
			}
		};
		
		
		/**
		 * Creates <code>IBuffer</code>s based on documents.
		 */
		protected class BufferFactory implements IBufferFactory {