This is a great change that will undoubtedly cause a lot of headaches.

There's a number of libraries (particularly around serialization/marshaling) which will end up mutating `final` fields. In fact, this is a trick I've pulled once or twice in my own code for "reasons" (generally needing to modify behavior of a library because it was deficient).

I suspect this will be one of those things that ends up requiring java devs everywhere to bump up the versions of the libraries they use.