Option to opt-out of rule 4 (Exclude all fields that do not have validation rules described)

[jpbochi]

In some cases, accepting unknown fields is acceptable. The closest rule I found for that on LIVR is any_object, but that is too inflexible.

If I want an object with a couple of required fields and other dynamic ones, is it possible? It would be extra nice if it were possible to define some validation rules for those extra fields.