nit: remove java version check for reflection args in build.gradle

[shikharj05]

Description

Follow-up for #5206 (comment)

Java 21 as default- https://github.com/opensearch-project/security/blob/main/build.gradle#L98-L99

• Category (Enhancement, New feature, Bug fix, Test fix, Refactoring, Maintenance, Documentation)
  Maintenance
• Why these changes are required?
  Maintenance
• What is the old behavior before changes and new behavior after changes?

Issues Resolved

Is this a backport? If so, please add backport PR # and/or commits #, and remove backport-failed label from the original PR.

Do these changes introduce new permission(s) to be displayed in the static dropdown on the front-end? If so, please open a draft PR in the security dashboards plugin and link the draft PR here

Testing

[Please provide details of testing done: unit testing, integration testing and manual testing]

Check List

• New functionality includes testing
• [NA] New functionality has been documented
• [NA] New Roles/Permissions have a corresponding security dashboards plugin PR
• [NA] API changes companion pull request created
• Commits are signed per the DCO using --signoff

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.
For more information on following Developer Certificate of Origin and signing off your commits, please check here.

[cwperks]

[CI / backward-compatibility (17, windows-latest) (pull_request)] - Should we consider upgrading the java version for the bwc tests?

[shikharj05]

[CI / backward-compatibility (17, windows-latest) (pull_request)] - Should we consider upgrading the java version for the bwc tests?

Should we keep one with Java 17 and upgrade Java 11 to 21? i.e. keep 17 & 21?

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 71.69%. Comparing base (c9e0edc) to head (0cfc57a).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5218      +/-   ##
==========================================
+ Coverage   71.64%   71.69%   +0.04%     
==========================================
  Files         337      337              
  Lines       22789    22789              
  Branches     3606     3606              
==========================================
+ Hits        16327    16338      +11     
+ Misses       4659     4647      -12     
- Partials     1803     1804       +1     

see 5 files with indirect coverage changes

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[cwperks]

Should we keep one with Java 17 and upgrade Java 11 to 21? i.e. keep 17 & 21?

We may need to take a closer look at the workflow. The workflow builds and runs the previous version and current version with the same JDK version despite being different major versions. We may want to split out the jdk for previous 2.x version vs jdk used for building and running the 3.x cluster.

One test we could do is create a small PR using a JDK 21 feature only in main and see if the bwc check fails to compile the main branch with JDK 11 or JDK 17