OpenAPI-aware Frameworks

There's a new breed of API-centric backend application frameworks popping up which take an exciting approach. Instead of asking you to tack the annotations in around the existing codebase, the frameworks simply produce OpenAPI for you from the actual code you're writing. Your application is already declaring routes, defining parameters and incoming validation logic, and helping serialize output. It makes a lot of sense for the framework to help produce this machine readable format for you, from the code you're already writing.