Related to #29162:

I've had several WTF + hours of debugging to finally understand I had to write my message classes in some idiomatic way to get it through a Messenger transport.

That's been definitely a bad experience to me. I think I'm not the only one going to fall into the trap.
We should find a way to close it. That's a significant DX issue to me. To be resolved in 4.3 I suppose.

Any ideas?