That fails in the presence of subtyping, unfortunately. A could expose a C in terms of some supertype not defined in C. Then that object gets cast back down to the more specific type and handed off to (the wrong version of) C.
Well, in that case, the same class from different versions of C should be considered distinct (i.e. when the compiler sees `a instanceof C.A`, it actually translates it into `a instanceof C_V1_53.A`, where the version is appropriate to the current module (and so is different if accessing `C.A` in modules `A`, `B`, or potentially the main program).
