private void installCallbackListener(@NotNull MergeRequest request) {
    MergeCallback callback = MergeCallback.getCallback(request);
    callback.addListener(new MergeCallback.Listener() {
      @Override
      public void fireConflictInvalid() {
        showInvalidRequestNotification();
      }
    }, this);

    if (!callback.checkIsValid()) {
      showInvalidRequestNotification();
    }
  }
private void installCallbackListener(@NotNull MergeRequest request)