Fix DelegatingRestHandlerTests

[reta]

Description

Fix DelegatingRestHandlerTests

Issues Resolved

Caused by opensearch-project/OpenSearch#13772

Is this a backport? If so, please add backport PR # and/or commits #

Testing

N/A

Check List

• New functionality includes testing
• New functionality has been documented
• Commits are signed per the DCO using --signoff

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[reta]

Come up in #4432 (comment) , thanks to @nibix

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 65.44%. Comparing base (0aed8f9) to head (1fd98c6).
Report is 4 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4434      +/-   ##
==========================================
+ Coverage   65.42%   65.44%   +0.02%     
==========================================
  Files         310      312       +2     
  Lines       22013    22042      +29     
  Branches     3556     3559       +3     
==========================================
+ Hits        14401    14426      +25     
- Misses       5841     5843       +2     
- Partials     1771     1773       +2     

Files	Coverage Δ
...nsearch/security/filter/DelegatingRestHandler.java	93.33% <100.00%> (+0.47%)	⬆️

... and 2 files with indirect coverage changes

[peternied]

What do you think about moving the delegating handler into core so this is avoided in future iterations?

[reta]

What do you think about moving the delegating handler into core so this is avoided in future iterations?

@peternied core has nothing to do with this change: in core the change is non-breaking and adds default method to RestHandler. The security plugin uses own DelegatingRestHandler and reflection APIs to check all RestHandler methods are "intercepted", the alternative here would be to use generated proxy (instead of hardcoded DelegatingRestHandler) in the security plugin.