Testing JsonSerializers for akka

Is there a simple way to verify that every type that needs to have a JsonSerializer registered has one?

We’re on lagom 1.4.4 and we just went from single node deployments to clustered deployments and ran into a bug in staging where we hadn’t defined JsonSerializers[T] for commands with ReplyType[T]. This is super annoying because it only seems to pop up in the clustered deploys – some of these commands are exercised in entity tests with java serialization disabled and this wasn’t causing problems.

I’m open to reflection-based tests, and would consider writing one if no one has.