They may already have, looks like that archived repository has been replaced with: https://github.com/heroku/heroku-buildpack-java https://github.com/heroku/her

They may already have, looks like that archived repository has been replaced with: https://github.com/heroku/heroku-buildpack-java https://github.com/heroku/heroku-buildpack-java which doesn't even use go. And they'd like you to even move away from that replacement to an ever newer replacement: https://github.com/heroku/buildpacks-jvm https://github.com/heroku/buildpacks-jvm