JsonSchema fail / warn on extra keys

[LeifW]

When using a schema generated by genericJsonSchema on a case class, is there a way to have it fail or warn on unrecognized keys? The use case is detecting if the end user typod one of the keys in their json - e.g. if they were supposed to submit {"name": "foo"}, and instead submitted {"nme": "foo"}, it might be nice to tell them "unrecognized key: 'nme'" (as well as "missing key": 'name'"), instead of just "missing key": 'name'".
Or perhaps a way to get access to the list of fields on that case class from the JsonSchema, so we could do that check ourselves?

[julienrf]

This need is not addressed by endpoints4s currently. It could be implemented in endpoints4s or outside of endpoints4s.