It took a lot of work to get there, and there's still lots of room for improvement. My ultimate goal is to automatically generate the API client test suite based on the requests/responses. I also want to add some custom logic and workflow rules to the OpenAPI specification, instead of needing to write custom wrapper code in 10+ languages.
I've had to write the same basic code so many times: Make a POST request, then make a GET request once per second until the "status" changes from "pending" to "done", and then finally return the completed result. (I know it would probably be better to set up a websocket connection, but this works fine and it was easier to implement.) It would be so awesome if I could define this workflow inside my API specification, and then the auto-generated client code could include this polling logic without any effort on my part. (Apart from needing to write and support the higher-level generator code for each language, which would actually be a lot more work.)
The other really annoying thing is needing to figure out package managers and release steps for every single programming language. I've only figured this out for 6 languages so far (C#, Java, JS, PHP, Python, Ruby), but I want to support far more languages, and it's just exhausting to go through this process each time. It would be so nice if there was an open source project that wrapped all of the different package managers and provided a framework on top of openapi-generator. And if there was a CLI tool (or web UI) that walked you through the process of signing up for accounts and setting up API keys, and then keeping it all in one place. I would honestly be tempted to rewrite openapi-generator from scratch in a better language / template engine, because the Java code is so hard to read and extend. I'm mainly a Ruby developer, but I don't think Ruby would be a great choice for CLI / generator tools, because it gets pretty slow. So maybe Python or Go.
I feel like this would a really interesting project to work on, and potentially a startup idea. Would anyone be interested in using it? I should probably try to validate this idea. I've set up a Google Form where you can just click a checkbox to register your interest anonymously, or you can also submit your email if you want to get updates and try a beta version: https://forms.gle/7qWzWpC9QrTjUgnU7