Refactor AbstractJavaCodegen and inheriting generators to allow use of modern Swagger annotations

[InfoSec812]

Description

In #2972, #6108, #5478, and many others there are complaints about old libraries/annotations being used in various Java generators. As a user of OpenAPI Generator who works in a number of Java toolkits/frameworks, I would like to see the AbstractJavaCodegen and all child generators updated to allow the use of the latest annotations and features of OpenAPI.

openapi-generator version

v5.0.0 Beta

Related issues/PRs

#2972, #6108, #5478

Suggest a fix/enhancement

I will be preparing a fork/branch which I will link in the comments below.

[InfoSec812]

The work I am doing will be track in this branch:

https://github.com/InfoSec812/openapi-generator/tree/Issue_7112-_-Refactor_AbstractJavaCodegen_and_inheritors

Design Goals:

1. MUST not break backward compatibility
2. SHOULD allow for more flexibility in choosing supporting libraries
   • Perhaps allowing variaous x- extensions to the API Spec will be a reasonable means
3. MUST allow for use of annotations which generate OpenAPI v3 output
4. MUST work with inheriting generators (or update them without breaking backward compatibility)
   • Spring/SpringBoot
   • JAX-RS
   • Vert.x
   • CXF
   • Play Framework
   • MSF4J
   • Jersey
   • Java Client

[InfoSec812]

To start, I think that adding a non-functional (for now) option in AbstractJavaCodegen which says something like preferOpenAPIv3 and then proceeding to update each set of templates from there makes sense. Any thoughts @macjohnny?

This would allow the default to continue using the existing templates/functionality and have no impact on backward compatibility. As the community goes through and adds support to the inheriting codegen implementations we could use that option as it becomes available.

[macjohnny]

@InfoSec812 Sounds good

[IncPlusPlus]

Is #27 related to this? Also, adding a reference to #4245 here so that they're linked as well. There are a lot of different issues filed for this exact issue. I think it might be a good idea to centralize them somewhere (maybe here?).

[InfoSec812]

@IncPlusPlus I would suspect that to be the case. I'm finally going to put some time into this.

[DNWEIJ]

Hello, was wandering if this has got some progress

[InfoSec812]

Not yet... My day job keeps getting in the way.

[ArthurEirich]

First of all, thank you, guys, for doing this great stuff. Is there any chance this feature will be added soon, @InfoSec812? Thank you once again and stay safe from Covid!

[InfoSec812]

I wish I had the time. There's so much which needs work and so few hours in the day.

[ArthurEirich]

Oh how I understand... Thanks, anyway, for quick response!

[guyhmerrill]

Is there a branch where these updates are being worked on? I might be able to help some. @InfoSec812

[InfoSec812]

I have made a few starts on this, but nothing worth mentioning. I just haven't had enough time to dedicate to making any significant progress.