Enables building on JDK 21 to prepare for the future.
Testing done
Ran mvn clean verify.
### 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 - that demonstrates feature works or fixes the issue
Enables building on JDK 21 to prepare for the future.
Testing done
Ran
mvn clean verify.