Regression in JRuby 9.0.0.0.pre2/rc1

foo.rb

require 'active_interaction'

module Bar
  class Foo < ActiveInteraction::Base
    string :foobar

    def execute
      # just return the string passed in, not important to reproduce the issue
      "#{foobar}"
    end
  end
end

Gemfile

source 'https://rubygems.org'

gem 'active_interaction', '2.0.1'

test.rb

require_relative 'foo'

puts Bar::Foo.run(foobar: "barfoo").result