Feature request

This is a follow up of #3849 , and of doctrine/dbal#4264

I tried your suggestion, and it seems the root cause is conditional return types are not supported: https://phpstan.org/r/bdef5abe-d824-4311-aa6e-e0cce31ede92

PHPDoc tag @phpstan-return has invalid value (($params is array{wrapperClass:mixed} ? T : Connection)): Unexpected token "$params", expected type at offset 82

Cc @pkruithof @morozov