Oh, that's nice. I was using it through Quarkus a while ago, not sure if I missed it or it wasn't available yet. That seems like a good starting point, although I assume it can't assure no runtime errors in production
Edit: it seems to me that GraalVM would benefit from a repository of classes and corresponding reflection configs. Like DefinitelyTyped from the Typescript world
It will track all uses of reflection during a program's execution. You can then use the resultant config as the starting point for the reflect-config.json.