Return types only when class is final

[phh]

Want to convert some of my docblocks to return types instead.

This used to work out of the box: https://tomasvotruba.com/blog/2019/01/03/how-to-complete-type-declarations-without-docblocks-with-rector/

However this was later changed: https://getrector.com/blog/how-to-automatically-add-return-type-declarations-without-breaking-your-code

However, now I can only get this to work if my class is final:

$rectorConfig->rule(AddVoidReturnTypeWhereNoReturnRector::class);

Not final: https://getrector.com/demo/d8df474f-2c1a-4787-b703-bf9de86dd3ce
vs final: https://getrector.com/demo/4477ed41-7ecb-49c5-8c6a-ef89177e06fe

Any way of making with work without making my class final?