Constructor type for Stuff classes. Clone instantiates backings with no
argument; hydration happens in a separate Hydrator.hydrate() step.
Classes may still define a raw-data constructor for direct test
construction — that's a class-local convenience, not a clone contract.
Constructor type for Stuff classes. Clone instantiates backings with no argument; hydration happens in a separate
Hydrator.hydrate()step. Classes may still define a raw-data constructor for direct test construction — that's a class-local convenience, not a clone contract.