Add Java21 branch support

[TharmiganK]

Purpose

Examples

Checklist

• Linked to an issue
• Updated the changelog
• Added tests
• Updated the spec
• Checked native-image compatibility
• Checked the impact on OpenAPI generation

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 80.28%. Comparing base (765fe10) to head (56b0d3d).
Report is 7 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #2196      +/-   ##
============================================
- Coverage     80.31%   80.28%   -0.04%     
  Complexity      669      669              
============================================
  Files           408      408              
  Lines         22994    22994              
  Branches       5277     5277              
============================================
- Hits          18468    18461       -7     
- Misses         3390     3399       +9     
+ Partials       1136     1134       -2     

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