Refactor coverage reporting workflow and add JaCoCo plugin

[bernardladenthin]

Summary

This PR refactors the CI/CD workflow to decouple coverage reporting from the publish jobs and adds JaCoCo code coverage instrumentation to the Maven build.

Key Changes

• New report job: Created a dedicated workflow job that runs after tests to handle coverage report uploads to Coveralls and Codecov, making the workflow more modular and maintainable
• Updated job dependencies: Changed publish-snapshot and publish-release jobs to depend on the new report job instead of directly on test
• Removed post-publish job: Eliminated the post-publish job that previously handled coverage reporting after successful publishes, consolidating this logic into the earlier report stage
• Added JaCoCo Maven plugin: Integrated JaCoCo 0.8.14 into the build to generate code coverage reports during the test phase
• Improved error handling: Both Coveralls and Codecov uploads now use continue-on-error: true to prevent workflow failures if coverage services are unavailable

Implementation Details

• JaCoCo is configured with two executions: prepare-agent (to instrument code during tests) and report (to generate coverage reports in the test phase)
• Coverage reports are now generated as part of the standard test execution, making them available for the dedicated report job
• The workflow now uploads coverage data earlier in the pipeline (after tests complete) rather than waiting for publish jobs to succeed

https://claude.ai/code/session_015QvayxAG8vHDVH1fcqUZ8w

[claude]

Review Summary

The changes look solid overall. The refactoring improves the CI pipeline structure by decoupling coverage reporting from publish jobs, and the JaCoCo configuration is correctly set up. A few items for consideration:

Strengths

✅ Cleaner dependency chain — Moving coverage reporting to a dedicated report job that runs after test but before publish-* is architecturally cleaner
✅ JaCoCo configuration — Both prepare-agent and report executions are correctly configured with proper phases
✅ Graceful failure handling — Both Coveralls and Codecov uploads use continue-on-error: true to prevent workflow failures if external services are unavailable
✅ Token fix — Switching from COVERALLS_TOKEN to GITHUB_TOKEN for the Coveralls action is correct per the commit message

Potential Concerns

1. Maven dependency submission without explicit Maven install — The report job runs maven-dependency-submission-action@v5 after checkout and Java setup, but doesn't explicitly invoke Maven or install Maven. The action should be self-contained, but verify in your test runs that dependency submissions complete successfully.

2. Artifact download assumes test job succeeded — The report job downloads the JaCoCo artifact with continue-on-error: true, so if the artifact doesn't exist, coverage upload will proceed with empty data. This is intentional but worth documenting if it becomes an issue.

Recommendation

Run a test workflow execution to verify that:

• The JaCoCo artifact is successfully generated and downloaded in the report job
• Coverage is successfully submitted to Coveralls and Codecov
• The maven-dependency-submission-action completes without errors

No blocking issues found.