Validate extra parameters on responses

[alfechner]

The docs state that strict_validation to disallow any extra parameters that are not defined in your specification for incoming request payloads.

However, the response payload always allows extra parameters. Even with validate_responses activated.

IMHO the validation of extra parameters in the response is more important than on the incoming request. Is that a design decision? If not, would you be open to a PR that activates the validation for extra parameters on responses if validate_responses and strict_validation both are active?

[alfechner]

I did simply not set additionalProperties to false. It's validated correclty.