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.