Symfony version(s) affected: 4.2.2

Description
I have a service that implements ParamConverterInterface that worked fine a few days ago, but when I run 'composer update', I can an error message that Doctrine cannot find the entity. This may be related to #29810

How to reproduce

I've attached my composer.json/lock
setup.zip

. Follow the instructions to create a ParamConverter. run composer install with my attached files. The controller should return a valid entity. Then run composer.update, now it will fail.

Sorry I can't provide a more precise way to reproduce this problem.