Provide a generator that can generate valid requests/responses from an Endpoint definition

[hochgi]

Following this conversation: It would be very helpful to have a tool that can generate requests & responses from an Endpoint definition.

Motivation: There are many ways we can use such a tool. In the scenario I describe in the original conversation, I speak of using such ability with e.g. scalacheck's Gen to create valid requests/responses. Those can then be tested against a given OpenAPI schema with tools like: swagger-request-validator.