The jirb_swing example application we ship with JRuby uses Swing to provide a GUI version of the IRB REPL. Currently, it has dependencies on jruby-readline, which may be leaving JRuby to match Ruby 3.3's removal of the readline extension. It also has not been verified fully working with the much more advanced modern IRB.

There are several tasks here:

• Remove jruby-readline dependency from jirb_swing, if it still exists.
• Move jirb_swing to its own gem and preinstall (bundle) it.
• Remove jruby-readline from JRuby altogether
• Update the readline gem to support loading jruby-readline in place of readline-ext, if installed.