Update Build Configuration for Java 17 Upgrade

[devin-ai-integration]

Update Build Configuration for Java 17 Upgrade

Summary

This PR updates the project's Java version from 11 to 17 as the first phase of the Java 17 upgrade plan. The changes include:

• build.gradle: Updated sourceCompatibility and targetCompatibility from '11' to '17'
• build.gradle: Updated Spotless plugin from 6.2.1 to 6.11.0 (required for Java 17 compatibility - the old version had module access issues with Java 17)
• .github/workflows/gradle.yml: Updated CI workflow to use JDK 17 with actions/setup-java@v3 and temurin distribution
• DefaultJwtServiceTest.java: Minor code formatting applied by Spotless

All local tests pass (68 tests), and the build completes successfully with Java 17.

Note: This is Phase 1 only. Spring Boot version and other dependencies remain unchanged and will be updated in a future PR.

Review & Testing Checklist for Human

• Verify CI passes completely - all tests and checks should pass in the GitHub Actions workflow
• Review Spotless plugin version update - The bump from 6.2.1 to 6.11.0 was necessary for Java 17 compatibility, but wasn't in the original scope. Confirm this is acceptable.
• Check for other configuration files - Consider if other places need Java 17 configuration updates (e.g., Dockerfile, deployment configs, IDE settings, README)

Test Plan

1. Let CI complete and verify all checks pass
2. If possible, test the application in a staging/dev environment to ensure runtime behavior is unchanged
3. Verify that the application starts up successfully and core features work

Notes

• Spring Boot 2.6.3 (current version) does support Java 17, so no compatibility issues are expected
• The Spotless plugin update was required because version 6.2.1 throws IllegalAccessError when trying to access Java compiler internals in Java 17
• Future PR will handle Spring Boot version upgrade and dependency updates

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Link to Devin run: https://app.devin.ai/sessions/079f8ee1ea4b43cca2f4fe93dc435ba7
Requested by: @alexjpeng

[devin-ai-integration]

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