What would be a good way to add custom Pydantic validators to the generated model?

[Iddodo]

First I want to start with a big thank you to the community for creating such a great package. It's been helping us a lot.

It would be nice to be able to add custom Pydantic validators to some of the classes that require non-trivial validation logic.

This would be helpful as the model is then consumed by FastAPI, which would run these validators during de-serialization.

While I understand this is probably not currently supported (unless I missed something), I was wondering if there was some way I could customize the codegen step such that these Pydantic validators can be added directly.