@NotNull
      @Override
      public Iterator<VirtualFile> getIn(VirtualFile n) {
        Set<String> classesInCurrentRoot = fromClasses.get(n);
        return toClasses.entrySet().stream()
          .filter(entry -> ContainerUtil.intersects(entry.getValue(), classesInCurrentRoot))
          .map(entry -> entry.getKey())
          .collect(Collectors.toSet()).iterator();
      }
@NotNull
      @Override
      public Iterator<VirtualFile> getIn(VirtualFile n)