How to get Authorizer Id from Resource Id in AWS SDK?

Question

I am using Java ApiGatewayClient and using it to return all resources by calling:

var res = apiGatewayClient.getResources(getResourcesRequest);

Now, according to sdk I should be able to get Authorizer id by res.items().get(0).resourceMethods().get("POST").authorizerId();

But I always recieve null value here, even though I cross checked from AWS, and AuthId exists and is in place.

I got all the resources and in them not even one had authId value other than null.

Is this is a bug from AWS, or am I doing something wrong here?

Any help is appreciated. Thanks.

Sample Response:

{
    "path": "/dummy/v1",
    "id": "x977w7",
    "resourceMethods": {
        "POST": {
             "authorizerId": null,
             "httpMethod": null,
             "operationName": null
         }
     }
}