How does Java mock-server framework return response with json format?

I need to mock external rest API services in the tests. Search for related frameworks, the mock-server looks like what I need: https://www.mock-server.com/#what-is-mockserver. However I am not able to find how I can mock the JSON formatted response. From the tutorial it provides such examples of requests, not the response. Is there a way to return response with JSON format?