Creating a LogStash plugin with Java instead of Ruby

I want to create a LogStash plugin that utilizes code written in Java and I need some help. Has anybody done this before?

I am not comfortable with Ruby. Unfortunately, I can see that LogStash plugins must be written in Ruby, and that I must create a plugin as a Ruby Gem ref.

I have noticed that LogStash actually uses JRuby ref, so it should be possible to write Ruby code that simply calls an attached jar. I have seen at least 3 different methods for attaching jars onto a Ruby Gem ref, but I don't know which one to use.

Does anybody have a suggestion? Or example code?

It looks like here is an example of integrating java code into a LogStash plugin using JRuby.

Check out logstash-input-kafka for a current plugin using Java classes.
Because Logstash uses jruby it is running on the JVM and you can use
whatever jars you want.