Fix "Test Connection" button when used with Jackson 2.16.1 or later

[bruderol]

Here is a pull request for the proposed solution as proposed and discussed on the issue #1605 - would be great if you could release that soon please.

Testing done?

When the most recent Jackson 2 API plugin (2.16.1.x) is used, compilation fails without this change and succeeds with this change. Interactive testing of the "Test connection" button confirms that the new code is well behaved

### Submitter checklist
- [x] Make sure you are opening from a **topic/feature/bugfix branch** (right side) and not your main branch!
- [x] Ensure that the pull request title represents the desired changelog entry
- [x] Please describe what you did
- [x]  Link to relevant issues in GitHub or Jira
- [x] Link to relevant pull requests, esp. upstream and downstream changes
- [x] Ensure you have provided tests

[MarkEWaite]

@krisstern and @harsh-ps-2003 I think that we should merge the pull requests and deliver the 1.8.0 release of the GitLab plugin. The pull requests are:

• 1606

• 1607

Does that seem reasonable for the two of you?

[krisstern]

@krisstern and @harsh-ps-2003 I think that we should merge the pull requests and deliver the 1.8.0 release of the GitLab plugin. The pull requests are:

• Fix "Test Connection" button when used with Jackson 2.16.1 or later #1606
• Require Jenkins 2.401.3 or newer #1607

Does that seem reasonable for the two of you?

Sure, this makes sense to me

[MarkEWaite]

Sure, this makes sense to me

Thanks. I'll plan to generate a release in a few hours.

[bruderol]

@MarkEWaite wow, I am impresed - thank you for testing and releasing it so fast. That was a great experience :-) Will immediately test the new release. Thanks so much.

And I can allready confirm, that the new release does not have that issue anymore. Thank you!