JVM support for JRuby apps is now provided by the `heroku/jvm` buildpack

Change effective on 24 February 2021

JRuby applications require the JVM to run. Before this change, the JVM for JRuby apps was provided by the heroku/ruby buildpack for JRuby applications.

Now the custom JVM installation logic in the heroku/ruby buildpack has been removed, and instead, the heroku/jvm buildpack will be called directly by the Ruby buildpack.

Instead of relying on this functionality, it is recommended to manually require the heroku/jvm buildpack for your application:

$ heroku buildpacks:add heroku/jvm --index=1

For more information on JRuby support, see the Heroku Ruby Support page.