feat: bump java clients openapi-generator to 6.0.0

[lrenard-qima]

Context : A bug has been fixed in the release 6.0.0 of openapi-generator. It fixes a NPE when trying to perform a PUT with an empty body while using the ApiClient generated with openapi-generator. Link to the fix on openapi-generator : https://github.com/OpenAPITools/openapi-generator/pull/12172

In my case I am having this error when calling Hydra Admin API to accept logout request. It is building a PUT request with an empty body and it ends up with a NPE.

Idea is to upgrade openapi-generator version to include the fix in generated ory/hydra-client-java.

For a more detailed overview of the bug I have created a ticket on ory/sdk repository that is mentionent below (in Related Issue or Design Document part)

BREAKING CHANGES: 

This patch bumps the version of openapi-generator used to generate Java clients from 5.4.0 to 6.0.0.

Related Issue or Design Document

Linked to bug ticket on ory/sdk : https://github.com/ory/sdk/issues/191

Checklist

• [x] I have read the contributing guidelines and signed the CLA.
• [x] I have referenced an issue containing the design document if my change introduces a new feature.
• [x] I have read the security policy.
• [x] I confirm that this pull request does not address a security vulnerability. If this pull request addresses a security vulnerability, I confirm that I got green light (please contact security@ory.sh) from the maintainers to push the changes.
• [ ] I have added tests that prove my fix is effective or that my feature works.
• [ ] I have added necessary documentation within the code base (if appropriate).

Further comments

[aeneasr]

Thank you! :) Are there breaking changes in the 6.0 generate that we need to be aware of?

[lrenard-qima]

Thank you! :) Are there breaking changes in the 6.0 generate that we need to be aware of?

You are welcome =) I have not investigated it enough. I leave the PR as a draft while I check that :)

[aeneasr]

Great, thanks!

[aeneasr]

Hi, I'm just echoing my message from slack:

Hi Lucas, thank you! I think the info that they fixed an important bug is enough for me to get it merged :slightly_smiling_face: For breaking changes, you can also always look at the release change log from open api generator itself: https://github.com/OpenAPITools/openapi-generator/releases/tag/v6.0.0#java

One last thing we need to do though is that we probably need to update the dependencies to match the 6.0 generator here: https://github.com/ory/sdk/tree/master/contrib/poms

When I upgraded to 5.4.0 these were the changes I had to make (please only look at the POM changes):

https://github.com/ory/sdk/commit/303c725db6c25bd41169387e0db90f69ab70963a

Regarding the question you had on slack, mix is from elixir so if you don't have it installed that will fail. A better option is to use what is written in the README:

https://github.com/ory/sdk#debugging-failing-circleci-tests

This will generate the code in your local file system!

[geetparekh]

Hello,

Curious as to in which version will the fix be available. We are also facing the same issue when calling Hydra Admin API to accept logout request. Thank you!

[aeneasr]

We updated the java generator