What was going on
A Java app using the moov-io/ach HTTP API needed both ways of creating files through `POST /files/{fileID}`: from a JSON body and from raw NACHA text. The OpenAPI-generated Java client only exposes one body schema per endpoint (a long-standing openapi-generator bug), so the raw-text path was unreachable. The generated method demanded a `CreateFile` object and wouldnt accept a plain string.
What fixed it
The maintainer first made the server ignore the Content-Type header and try parsing as both JSON and NACHA, which fixed the server side, but the generated Java client still couldnt send a raw string because of the generator bug. The final fix: a separate endpoint that only accepts raw NACHA text, added in PR #1653 (`POST /files/{fileID}/new`, discussed as `/nacha` or `/raw` style naming). The reporter confirmed "Yes, we can work with this."
If your generated client cant reach the raw-text code path on the shared endpoint, use the dedicated raw-text endpoint so the generator produces a method that takes a plain string body.