private void convertToIntSet() {
    IntSet idSet = new IntOpenHashSet(weirdFiles.size());
    for (Iterator<VirtualFile> iterator = weirdFiles.iterator(); iterator.hasNext(); ) {
      VirtualFile wf = iterator.next();
      if (wf instanceof VirtualFileWithId) {
        idSet.add(((VirtualFileWithId)wf).getId());
        iterator.remove();
      }
    }
    this.idSet = idSet;
  }
private void convertToIntSet()