Auto-generating JSON schemas to test in Postman

I need to test the schemas of a large number of API endpoints. My team uses Swagger, which does provide “models” (basically JSON schemas) for the objects they require in their requests. But what tools, if any, exist that will look at what’s happening on the server side to generate a JSON return object?

Ultimately, it’d be great if I could update the schemas within some set of Postman collection or environment variables every time any return object’s schema changed.