spider: SAST (SonarLint) Fixes

[kingthorin]

Overview

• Use isEmpty vs length checks.
• Use instanceof assignment where applicable.
• Use text blocks vs concatenation where applicable.
• Use computeIfAbsent vs get/put where applicable.
• Use charset constants from JRE vs string literals.
• Use constants from base classes vs extended classes.
• Remove useless conditions/assignments.

Related Issues

n/a

Checklist

• [ ] Update help
• [x] Update changelog
• [x] Run ./gradlew spotlessApply for code formatting
• [ ] Write tests
• [x] Check code coverage
• [x] Sign-off commits
• [x] Squash commits
• [x] Use a descriptive title

[psiinon]

Checkmarx One – Scan Summary & Details – f49ee7fa-231e-45be-9160-633048f47566

Great job! No new security vulnerabilities introduced in this pull request

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