@Nullable
  @RequiresEdt
  private ProgressIndicator startLoading() {
    if (myRequests != null) return null;

    return BackgroundTaskUtil.executeAndTryWait(indicator -> {
      ListSelection<? extends DiffRequestProducer> producers = loadRequestsInBackground();
      return () -> {
        indicator.checkCanceled();
        applyLoadedChanges(producers);
      };
    }, null);
  }
@Nullable
  @RequiresEdt
  private ProgressIndicator startLoading()