@Nullable
    @Override
    public DiffRequestProducer createProducer(@Nullable Project project) {
      if (change.getBeforeRevision() instanceof FakeRevision || change.getAfterRevision() instanceof FakeRevision) {
        LoadingDiffRequest request = new LoadingDiffRequest(ChangeDiffRequestProducer.getRequestTitle(change));
        return new ErrorChangeRequestProducer(change, request);
      }

      ChangeDiffRequestProducer producer = ChangeDiffRequestProducer.create(project, change);

      if (producer == null) {
        ErrorDiffRequest request = new ErrorDiffRequest(DiffBundle.message("error.cant.show.diff.message"));
        return new ErrorChangeRequestProducer(change, request);
      }

      return producer;
    }
@Nullable
    @Override
    public DiffRequestProducer createProducer(@Nullable Project project)