I came across this issue when trying out one of my libraries on jruby 9000 pre2. The relevant source code is here: https://github.com/Saltside/thrift-base64-ruby/blob/master/lib/thrift/base64.rb#L22-51

Note the comment about using prepend and included. The code fails on 9000.pre2 like so:

NoMethodError: private method `included' called for Thrift::Struct:Module
          included at /usr/local/bundle/gems/thrift-base64-0.1.1/lib/thrift/base64.rb:35
           include at org/jruby/RubyModule.java:2408

I could remove my work around and use included like normal, but it seems strange that a method would change scope when invoked with super.

This is easily to replicate. Clone that library and run the tests on 9000.pre2.