Is there a way to automatically create an API mockup from a Swagger file that produces different outputs depending on the request body?

I've been using Postman's API mockup features, but they are not smart enough to detect when a field is missing from the body and send a different response depending on the validity of a request (it can only do it with url parameters in GET requests).

Is there any solution that is able to parse a swagger/openapi file and create those programatic differences?