feat: Performance enhancements

[chrfwow]

This Pr introduces some performance enhacements, that together yield the following results:

Baseline (AllocationBenchmark.main run five times with the IntelliJ Profiler and averaged): runtime: 5329 ms memory allocations: 16.47 GB

This PR: runtime: 5404ms (no significant change, the deviation of runs is quite large) memory allocations: 14.62 GB

[codecov[bot]]

Codecov Report

:x: Patch coverage is 96.87500% with 1 line in your changes missing coverage. Please review. :white_check_mark: Project coverage is 93.66%. Comparing base (ab04409) to head (293c062). :warning: Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
...n/java/dev/openfeature/sdk/ImmutableStructure.java	90.00%	0 Missing and 1 partial :warning:

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #1741      +/-   ##
============================================
+ Coverage     92.51%   93.66%   +1.15%     
- Complexity      593      601       +8     
============================================
  Files            53       55       +2     
  Lines          1403     1406       +3     
  Branches        150      154       +4     
============================================
+ Hits           1298     1317      +19     
+ Misses           64       50      -14     
+ Partials         41       39       -2     

Flag	Coverage Δ
unittests	93.66% <96.87%> (+1.15%)	:arrow_up:

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[toddbaert]

/gemini review

[toddbaert]

I'll merge this one tomorrow @chrfwow . Up to you if you want to address the minor Gemini issues.

[sonarqubecloud[bot]]

Quality Gate passed

Issues
1 New issue
0 Accepted issues

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

See analysis details on SonarQube Cloud