Those kinds of systems are a real joy if designed correctly. You can usually pretty safely assume that the object does not mutate (much), and you can very easil

Those kinds of systems are a real joy if designed correctly. You can usually pretty safely assume that the object does not mutate (much), and you can very easily find out what you need to do to pass that object forward into a function that requires RequestWithId. Look up the concept of "make illegal states unrepresentable." EDIT: RequestWithoutId is not the best example of this, but the point remains