Step 1. Files get autogenerated (for example based on an OpenAPI spec.)
Step 2. We need to customized them.
Step 3. We need to regenerate them (e.g. the OpenAPI spec has changed)
Step 4. How do we re-apply the changes we made in Step 2.
This Workflow doc outlines how we could use some simple shell scripts based on diff and patch to achieve the result.