sharing definitions between APIs

What's the recommended way to have two different APIs share some data definitions with Guardrail?

Swagger allows extracting definitions into their own files and referencing them with `$ref`. For multiple swagger specs (multiple APIs) to share the same definitions file, would it be possible to run Guardrail 3 times -- once to generate just definitions, then once per swagger spec to generate the server code, but skipping codegen for definitions? Or maybe generating definitions twice but in the same namespace?