Mapping of String to Type

I am currently trying to write a method that takes a JSON (what API does not matter here) and validates it. I want the method to look something like this:

def validateJson(json, expectedType: Map[String, Type(?)], allowedVals: Map[String, expectedType(key)]): Boolean

The problem is: I do have a method jsonfield.validate[expectedType] but I do not know how to pass an unknown number of useable type parameters associated with strings to a method.

I'd gladly use some runtime reflection if that is possible here, or any advanced feature necessary to make this work easily. Any suggestions appreciated.

PS: I am using Play Framework 2.6.3