JRuby 1.7.20 now available on Heroku

Change effective on 05 May 2015

The Ruby stack now supports JRuby 1.7.20.

To use JRuby 1.7.20, add this to your Gemfile:

ruby '1.9.3', :engine => 'jruby', :engine_version => '1.7.20'

The JRuby release notes can be found on the JRuby website.