Create PaperMC plugin to auto-update ViaVersion

[Copilot]

• Create PaperMC plugin source
• Add GitHub Actions Maven build workflow
• Fix Java version: bump pom.xml and workflow from 17 → 21 (Paper API 1.21.4 requires Java 21)

Original prompt

Create an advanced PaperMC Plugin that auto updates ViaVersion to the latest version.

[windcolor-dev]

Hey is it able to detect the name of the old jar?

[Copilot]

Hey is it able to detect the name of the old jar?

Yes — the plugin scans the plugins/ folder for any .jar file whose name starts with viaversion (case-insensitive) via the findExistingViaVersionJar method in UpdateChecker.java. It handles arbitrary version suffixes (e.g. ViaVersion-4.9.2.jar, ViaVersion-5.0.0-beta1.jar). Once a newer version is downloaded, the old jar is deleted by name.

[windcolor-dev]

Final change:
Run a maven workflow to build the jar and upload it onto github

[Copilot]

Final change:
Run a maven workflow to build the jar and upload it onto github

Done in ab77fa6. Added .github/workflows/build.yml which:

• Runs mvn package on pushes to main, pull requests against main, and manual dispatches
• Uploads the built jar as a workflow artifact on every run
• Creates a GitHub Release with the jar attached whenever a v* tag is pushed