@Nullable
  public VcsInvalidated retrieveScopes() {
    ActionCallback callback = new ActionCallback();
    DirtBuilder dirtBuilder;
    synchronized (LOCK) {
      if (!myReady) return null;
      LOG.assertTrue(myDirtInProgress == null);

      dirtBuilder = myDirtBuilder;
      myDirtInProgress = dirtBuilder;
      myDirtBuilder = new DirtBuilder();
      myRefreshInProgress = callback;
    }
    return calculateInvalidated(dirtBuilder, callback);
  }
@Nullable
  public VcsInvalidated retrieveScopes()