Prepare for 2026-12 M2 - #481

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/checkout@v4, actions/setup-java@v4, actions/upload-artifact@v4, stCarolas/setup-maven@v5. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/

No files were found with the provided path: **/configuration/org.eclipse.equinox.simpleconfigurator/bundles.info. No artifacts will be uploaded.

setup-java v4 is deprecated and will no longer receive updates. Please migrate to actions/setup-java@v5.