private <X, Y extends AmazonWebServiceRequest> Response<X> invoke(Request<Y> request, HttpResponseHandler<AmazonWebServiceResponse<X>> responseHandler,
            ExecutionContext executionContext) {

        return invoke(request, responseHandler, executionContext, null, null);
    }
Normal invoke with authentication. Credentials are required and may be overriden at the request level.
aws-java-sdk-ec2instanceconnect/src/main/java/com/amazonaws/services/ec2instanceconnect/AWSEC2InstanceConnectClient.java