How to write AWS Lambda in Java, to consume query string parameters?

There are many similar threads out there, so I'll try to be simple and specific.

My API Gateway has GET method, without "Use Lambda Proxy integration" check marked. (Yes, to make my life little bit more difficult)

• My assumption is that I have API Gateway portion working correctly, with query string parameters.
• It has been deployed through Deploy API button

I also have mapping template written, as exactly said by this instruction provided by AWS.

Now, in java, I have the following:

public APIGatewayProxyResponseEvent handleRequest(APIGatewayProxyRequestEvent event, Context context) {

The concern is that event object is empty. Have I not been using the correct request event object?

ADDITIONAL NOTE

Per request, here's my lambda function below:

LambdaLogger logger = context.getLogger();
logger.log("EVENT: " + gson.toJson(event));

And here's what CloudWatch prints:

EVENT: {}