[BUG][OCaml] Incorrect support of JSON fields not in snake_case

[sir4ur0n]

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator (example)?
• Have you tested with the latest master to confirm the issue still exists?
• Have you searched for related issues/PRs?
• What's the actual output vs expected output?
• [Optional] Sponsorship to speed up the bug fix or feature request (example)

Description

When JSON fields are not in snake_case (e.g., someField), parsing fails because the field is expected to be named some_field).

openapi-generator version

7.10.0

OpenAPI declaration file content or url

https://api.integration.app/docs-json

Generation Details

$ openapi-generator-cli generate \
  --generator-name ocaml \
  --input-spec docs-json

Steps to reproduce

$ openapi-generator-cli generate \
  --generator-name ocaml \
  --input-spec docs-json

Related issues/PRs

N/A.

Suggest a fix

The generator uses ppx_deriving_yojson which supports an annotation [@key "someField"].
See https://github.com/ocaml-ppx/ppx_deriving_yojson?tab=readme-ov-file#key

I think a simple solution is to add this annotation on every single field