@NotNull
 @Override
 public FileStatus getElementStatus(final RefEntity element) {
   final GlobalInspectionContextImpl context = getContext();
   if (!isDisposed() && context.getUIOptions().SHOW_DIFF_WITH_PREVIOUS_RUN) {
     if (myOldProblemElements != null) {
       final boolean old = RefUtil.contains(element, myOldProblemElements.keySet());
       final boolean current = RefUtil.contains(element, getProblemElements().keySet());
       return calcStatus(old, current);
     }
   }
   return FileStatus.NOT_CHANGED;
 }
 @Override
 public Map<String, Set<RefEntity>> getOldContent() {
   if (myOldProblemElements == null) return null;
   final Map<String, Set<RefEntity>> oldContents =
       new com.intellij.util.containers.HashMap<String, Set<RefEntity>>();
   final Set<RefEntity> elements = myOldProblemElements.keySet();
   for (RefEntity element : elements) {
     String groupName =
         element instanceof RefElement
             ? element.getRefManager().getGroupName((RefElement) element)
             : element.getName();
     final Set<RefEntity> collection = myContents.get(groupName);
     if (collection != null) {
       final Set<RefEntity> currentElements = new HashSet<RefEntity>(collection);
       if (RefUtil.contains(element, currentElements)) continue;
     }
     Set<RefEntity> oldContent = oldContents.get(groupName);
     if (oldContent == null) {
       oldContent = new HashSet<RefEntity>();
       oldContents.put(groupName, oldContent);
     }
     oldContent.add(element);
   }
   return oldContents;
 }