@Override
  public boolean contains(Object file) {
    if (file instanceof VirtualFileWithId) {
      BitSet ids = fileIds;
      int id = ((VirtualFileWithId)file).getId();
      if (ids != null) {
        return ids.get(id);
      }
      IntSet idSet = this.idSet;
      if (idSet != null) {
        return idSet.contains(id);
      }
    }
    return weirdFiles.contains(file);
  }
@Override
  public boolean contains(Object file)