[BUG][Java] `$ref` with `multipart/form-data` is always null

[jeffshee]

Bug Report Checklist

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

Description

As titled, when a property is referenced using $ref with multipart/form-data in the requestBody, such property is always null. It works otherwise when not using $ref, or when not using multipart/form-data. This issue might only occur with the above combinations.

openapi-generator version

I tested with docker images of openapi-generator-cli v5.2.0 and v5.4.0. Both have the same issue. I couldn't test with the latest docker images v6.0.1. The server gives HTTP error 503 for all requests and refuses to work. This is also the reason why I couldn't test with the latest master. (This would be another issue.)

OpenAPI declaration file content or url

For the source codes to reproduce the issue, please refer to this repo: https://github.com/jeffshee/openapi-test The OpenAPI declaration file can be found here: https://github.com/jeffshee/openapi-test/blob/master/api.yaml

Generation Details

Steps to reproduce

Docker environment is required for using the Makefile provided in the repo.

1. Clone the repo.
2. Execute make all to compile and run the docker image.
3. Test the APIs run at http://localhost:8080/v1. test1 is not working. For comparison, test2 and test3 are working.

Related issues/PRs

N/A

Suggest a fix

N/A

[jeffshee]

Hi, how is this issue going? Do you need any additional info?

[RomioSahoo]

Tried out using a workaround from https://github.com/OpenAPITools/openapi-generator/issues/10415#issuecomment-1003067496 and it fixes the issue.

[jeffshee]

@RomioSahoo Thanks. Did you tried the workaround with the test source code that I provided above? I tried adding the option --global-property skipFormModel=true to the generator and it didn't fix the issue.