Require Java 21 in plugin pom

[NotMyFault]

Twin of jenkinsci/pom#781

[jglick]

I am trying to refresh my memory of how we handled Java bumps in the past, but I think this should be reverted (other than the 6 major version—too late!) and deferred. jenkinsci/jenkins#26018 has not even been released in a weekly yet, so where did the 2.516 dep come from? And the whole point of jenkinsci/maven-hpi-plugin#323 + #523 was that we would not need to make these incompatible changes to the plugin POM merely in order to support plugins which wish to depend on recent jenkins.versions that require a newer Java. Instead, that would be automatic, and then as a matter of cleanup we would bump the minimum core (to the first weekly using that Java version) and the fallback default Java version in the plugin POM some months after the new requirement appears in an LTS release, at which point by the guidelines most plugins would be able to pick up the bump anyway. Compare the merge timing of #478 to the announcements and changelog.

[NotMyFault]

I wasn't aware of jenkinsci/maven-hpi-plugin#323, we can surely roll this release back, no?

[jglick]

we can surely roll this release back, no?

Well, it would be a 6.x version, if anyone cares.

Ping @timja / @MarkEWaite / @jtnord in case anyone else has more context on this.

[jtnord]

I wasn't aware of jenkinsci/maven-hpi-plugin#323, we can surely roll this release back, no?

yes, the properties should get overridden when the hpi-plugin runs to set the compiler release etc based on the version of Jenkins in use.

[NotMyFault]

Will revert this evening and locations I've bumped it.

[jglick]

and locations I've bumped it

No need I think. AFAICT there is not much harm in the current release; it just cannot be used in plugins using somewhat older jenkins.versions. So it should suffice to push out a new release reverting this PR (minus the major version) and let people update to that normally. Later in 2026, when the LTS requiring 21+ is widely adopted, it should be OK to restore it.

[uhafner]

I wasn't aware of jenkinsci/maven-hpi-plugin#323, we can surely roll this release back, no?

yes, the properties should get overridden when the hpi-plugin runs to set the compiler release etc based on the version of Jenkins in use.

But that does not work with the enforcer properties, or am I doing something wrong? When I set a dependency to Jenkins 2.545 then I get:

[ERROR] Failed to execute goal org.apache.maven.plugins:maven-enforcer-plugin:3.6.2:enforce (display-info) on project analysis-pom: 
[ERROR] Rule 5: org.codehaus.mojo.extraenforcer.dependencies.EnforceBytecodeVersion failed with message:
[ERROR] Found Banned Dependency: org.jenkins-ci:task-reactor:jar:1.10
[ERROR] Found Banned Dependency: org.jenkins-ci:symbol-annotation:jar:1.26
[ERROR] Found Banned Dependency: org.jenkins-ci.main:jenkins-core:jar:2.545
[ERROR] Found Banned Dependency: org.jenkins-ci.main:websocket-spi:jar:2.545
[ERROR] Found Banned Dependency: org.kohsuke.stapler:stapler:jar:2065.v7db_c1fcf0a_d0
[ERROR] Found Banned Dependency: org.kohsuke.stapler:stapler-groovy:jar:2065.v7db_c1fcf0a_d0
[ERROR] Found Banned Dependency: org.kohsuke.stapler:stapler-jelly:jar:2065.v7db_c1fcf0a_d0
[ERROR] Found Banned Dependency: org.jenkins-ci.main:cli:jar:2.545
[ERROR] Use 'mvn dependency:tree' to locate the source of the banned dependencies.
[ERROR] -> [Help 1]

[timja]

But that does not work with the enforcer properties, or am I doing something wrong? When I set a dependency to Jenkins 2.545 then I get:

Is that with:
#1337

I tried on credentials plugin after updating the parent pom to latest and it worked fine.

[uhafner]

No, without. When I remove the enforcer properties in jenkinsci/analysis-pom-plugin#1461, then my build fails with the message from above.

But maybe this is a problem in my parent pom, I haven't tried without it.