Roadmap for 4.0

I've been keeping a wishlist of ideas that might appear in the following version:

• Extract Respect\Parameter\Reflector from ContainerResolver - a leftover from the interface migration that puts reflectCallable and acceptsType into a final abstract utils-like class called Reflector.
• Fail on unresolved parameters (by throwing an CannotResolveParameterException). That would unlock stackable resolvers (try one, then try the next, and so on).
• StackedResolver - meta-class for stacking Resolver.php implementations (assuming they throw).
• Split behaviors of the current resolver into stackable components the users can choose from (position, pull from container, infer by type, variadic fill, etc). Instead of a long procedure, the mechanism would be OOP-stack based.

These changes would promote a clearer API, be very small, and enable foreign implementors to add their own layering (which is impractical today, like caching and exotic specific resolvers).

Start by reading Resolver.php and the current ContainerResolver implementation, then trace how reflectCallable, acceptsType, and parameter resolution are used. The roadmap mentions extracting Reflector, adding CannotResolveParameterException and StackedResolver, and splitting resolver behaviors, but it does not define a single acceptance target; completion would require an agreed design and scope.