@Nullable
  Set<VirtualFile> takeAccumulatedFilesWithIndexProblems() {
    if (SKIP_INDEX_REPAIR_ON_ERROR) return null;
    Set<VirtualFile> filesWithProblems = myFilesHavingProblems.get();
    if (filesWithProblems != null) myFilesHavingProblems.set(null);
    return filesWithProblems;
  }
@Nullable
  Set<VirtualFile> takeAccumulatedFilesWithIndexProblems()