sortField and sortDirection parameters in AWS AppSync GraphQL API for flutter (aws amplify)

I'm developing flutter project on Aws amplify with AWS AppSync GraphQL API connected Dynamo DB.

Using CLI, sortDirection parameter works well.

But response.data always has null when I use sortDirection parameter on AWS AppSync GraphQL API.

I think that AWS AppSync does not provide built-in support for sortField and sortDirection parameters.

Is it right?

If I'm right, is there any way to fetch data sorted in descending order with using the API issued by AppSync?