RuntimeWiring is very silent at the moment when you configure it wrong: a wrong type or not existing field registered is just accepted.

This leads often to subtle problems, especially when bootstrapping or just prototyping something.

We should offer a simple Validator test util or maybe make the Wiring optionally more strict.

A more complex problem: The return type of a DataFetcher could be validated against the Schema. When you return for example a Dog object and the DataFetcher is registered for a type returning a Dog we could validate that the field of Java class type Dog matches the Schema type Dog. This needs more exploration/discussion.