1. Synchronizing on trivial properties (otherwise you couldn't use `public` anyway!) is an anti-pattern, as it's a too fine-grained unit of concurrency and invites race conditions.

2. Can't proxy without rewriting byte code, you mean.

3. Of course you can evolve, it's just a breaking ABI change so it requires a trivial code migration on the side of the callee. If the cost of that migration is too high, something else is wrong.