Fix warnings from new ErrorProne rules

[uhafner]

ErrorProne has some new detectors that cause new warnings.

[github-actions]

☀️   Quality Monitor

Tests

     Unit Tests: 100% successful (86 passed, 2 skipped)
   ⛔   Architecture Tests: 100% successful (17 passed)

Code Coverage

   〰️   Line Coverage: 92% (61 missed lines)
   ➰   Branch Coverage: 91% (19 missed branches)

Mutation Coverage

     Mutation Coverage: 80% (80 survived mutations)
   💪   Test Strength: 85% (58 survived mutations in tested code)

Style

     CheckStyle: No warnings
     PMD: No warnings

Bugs

     SpotBugs: No bugs
   🐛   Error Prone: No bugs

API Problems

   🚫   Revapi: No warnings

Vulnerabilities

   🛡️   OWASP Dependency Check: No vulnerabilities

Software Metrics

   🌀   Cyclomatic Complexity: 376 (total)
   💭   Cognitive Complexity: 173 (total)
   ➿   N-Path Complexity: 340 (total)
   📏   Lines of Code: 4270 (total)
   📝   Non Commenting Source Statements: 1257 (total)
   🔗   Class Cohesion: 71.43% (maximum)
   ⚖️   Weight of Class: 100.00% (maximum)

🚦 Quality Gates

Overall Status: ✅ SUCCESS

✅ Passed Gates

• ✅ Tests Success Rate: 100.00 >= 100.00
• ✅ Line Coverage: 92.00 >= 90.00
• ✅ Branch Coverage: 91.00 >= 90.00
• ✅ Potential Bugs: 0.00 <= 0.00
• ✅ Style Violations: 0.00 <= 0.00

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Created by Quality Monitor v3.2.0-SNAPSHOT-2 (#3a99f2e). More details are shown in the GitHub Checks Result.