aws api gateway – Authenticating a REST API with Cognito using AWS Amplify & Android-ThrowExceptions

Exception or error:

I am currently trying to configure a REST API I added using AWS Amplify. I have already configured user authentication in which users can sign-up and sign-in by following the steps outlined in the authentication docs. I then added a REST API using the api steps.

At the moment, I am just trying to retrieve a list of items from DynamoDB. The api is successful when I test it on the aws console, however, when I make the call from my android api, it returns the following error:

{"message":"Authorization header requires 'Credential' parameter. Authorization header requires 'Signature' parameter. Authorization header requires 'SignedHeaders' parameter. Authorization header requires existence of either a 'X-Amz-Date' or a 'Date' header. Authorization=[a long string of characters]

I understand that amplify automatically sets the API to be restricted using AWS_IAM, which I think is why the above message is returned. I am trying to get it to authenticate using the user pools I setup before with the authentication steps. The code in my android that app that makes the call to the API is as follows:

RestOptions options = new RestOptions("/models");

Amplify.API.get("modelsapi", options, new ResultListener<RestResponse>() {
    @Override
    public void onResult(RestResponse restResponse) {
        Log.i(TAG, restResponse.toString());
        Log.i(TAG, restResponse.getData().asString());
    }

    @Override
    public void onError(Throwable throwable) {
        Log.e(TAG, throwable.toString());
    }
});

Do I need to setup a Authorizer on AWS api console? And if so, How do I pass the authorization header with the user token. I have a seen a few responses from people using react native but not with android: AWS-amplify Including the cognito Authorization header in the request

The function which the Api invokes is as follows if needed:

app.get(path, function(req, res) {

  let queryParams = {
    TableName: tableName
  }

  dynamodb.scan(queryParams, (err, data) => {
    if (err) {
      res.statusCode = 500;
      res.json({error: 'Could not load items: ' + err});
    } else {
      res.json(data.Items);
    }
  });
});

Any points/help would be greatly appreciated! Thanks!

How to solve:

Have figured it out. Even though Amplify is meant to take the credentials automatically when making an API call, it seemed to throw up the unauthorized error anyway. When I tested using the console it worked fine. I had to manually add the authorization header to the Rest options:

RestOptions options = RestOptions.builder()
                .addPath("models")
                .addHeader("Authorization", token.getTokenString())
                .build();

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