Upgrade kubernetes-client-api to 6.8.1

[julieheard]

Downstream of jenkinsci/kubernetes-client-api-plugin#221

Testing done

I ran mvn verify to test locally and all working, all tests passing

### 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
- [ ] Link to relevant issues in GitHub or Jira
- [x] Link to relevant pull requests, esp. upstream and downstream changes
- [ ] Ensure you have provided tests - that demonstrates feature works or fixes the issue

[rsandell]

Just need to remember to update to the "real" version when it is released.

[Vlatombe]

@julieheard Need to bump jenkins.version here.

[2023-08-29T13:30:25.903Z] Caused by: org.apache.maven.plugin.MojoExecutionException: Dependency org.jenkins-ci.plugins:kubernetes-client-api:jar:6.8.1-224.vd388fca_4db_3b_ requires Jenkins 2.401.1 or higher.

[Vlatombe]

@julieheard I can't update this PR so you need to fix it.

[julieheard]

I am on it, when testing locally it also wants bumps for bouncycastle-api:2.27, okhttp-api:4.10.0-132.v7a_7b_91cef39c and jackson2-api:2.15.1-344.v6eb_55303dc3e

[julieheard]

Due to the Jenkins bump I have also bumped Kotlin and included three new dependencies (bouncycastle-api, jackson2-api, okhttp-api) as they were creating RequireUpperBoundDeps errors.

I came accross a strange issue with a test, mvn verify it was failing intermittently with this message:

[ERROR] Tests run: 10, Failures: 0, Errors: 2, Skipped: 0, Time elapsed: 2.661 s <<< FAILURE! -- in com.cloudbees.jenkins.plugins.kubernetes_credentials_provider.convertors.CertificateCredentialsConvertorTest
[ERROR] com.cloudbees.jenkins.plugins.kubernetes_credentials_provider.convertors.CertificateCredentialsConvertorTest.failsToConvertWhenCertificateCorruptBase64 -- Time elapsed: 0.015 s <<< ERROR!
java.lang.NoSuchMethodError: 'org.hamcrest.Matcher org.hamcrest.CoreMatchers.allOf(org.hamcrest.Matcher, org.hamcrest.Matcher)'
[ERROR] com.cloudbees.jenkins.plugins.kubernetes_credentials_provider.convertors.CertificateCredentialsConvertorTest.failsToConvertWhenCertificateCorruptPKCS12 -- Time elapsed: 0.006 s <<< ERROR!
java.lang.NoSuchMethodError: 'org.hamcrest.Matcher org.hamcrest.CoreMatchers.allOf(org.hamcrest.Matcher, org.hamcrest.Matcher)'

Digging into this I think it is a conflict between junit and hamcrest, I do not think it is due to the changes made in this PR.

[Vlatombe]

java.lang.NoSuchMethodError: 'org.hamcrest.Matcher org.hamcrest.CoreMatchers.allOf(org.hamcrest.Matcher, org.hamcrest.Matcher)'

Can't reproduce on my side, and I only see one hamcrest copy in the classpath

+- junit:junit:jar:4.13.2:test
|  \- org.hamcrest:hamcrest-core:jar:2.2:test
+- org.hamcrest:hamcrest:jar:2.2:test

[julieheard]

I have re-ran this test quite a few times today and also now can't reproduce. Must have been a small glitch in the classpath or something silly. This PR is now ready to merge 🙂

@agentgonzo or @jtnord would you mind merging as the upstream PR has now been merged? Many thanks 🙂

[jonesbusy]

Any update there ? Is confusing to have the kubernetes-api client available for upgrade but not all consumer upgraded.

Specially for people upgrading regulary their Jenkins plugins.

Thanks!

[jtnord]

The plugin does not depend on these and so they should not be needed. What is the rationale for the the creep in dependencies?

Due to the Jenkins bump I have also bumped Kotlin and included three new dependencies (bouncycastle-api, jackson2-api, okhttp-api) as they were creating RequireUpperBoundDeps errors.

perhaps you just need to pickup a newer bom version, at any rate - they are not plugin dependencies so should not be added to the dependencies section, rather dependencyManagement if they are not available in a newer bom