@Nullable
      @Override
      public Iterable<VirtualFile> getChildrenIterable(@NotNull VirtualFile f) {
        return f.isDirectory() && f instanceof NewVirtualFile ? ((NewVirtualFile)f).iterInDbChildren() : null;
      }
@Nullable
      @Override
      public Iterable<VirtualFile> getChildrenIterable(@NotNull VirtualFile f)