We have the situation in the docs that parameters declared as arrays do not follow the typehinting rules, but parameters as class names do. Re-using the callback from the docs could get confusing when extensions start to typehint on it, but not the core..

I think there is a subtle difference between a callback, and a callable. In javascript for example, callback is something that is executed on certain events "onsuccess" is the typical example. There is nothing that says the callable parameter gets executed as a part of an event, and I think the default usecase would be to execute it right away (f.e. filtering data).

I think I would prefer callable, but I could live with either.