Interesting scenario, I guess we could try to support that.

A custom BytecodeProvider can still be provided, the difference is that the way in which one is specified was changed; now it can be done in theory by changing the registered BytecodeProvider service at bootstrap time, but I believe that wouldn’t help you much in this case as a SerializableProxy really expect this to be our ByteBuddy based implementation; this could be improved on, but some patches would be necessary.

A better fix could be to inject a LazyInitializer which throw an error at runtime, if/when it gets triggered? Essentially replaing the cases in which today we throw an IllegalStateException to actually accept this case but making it use such a lazy initializer.