I wasn’t able to create a reduced version, so here are the full reproduction steps:

1. git clone https://github.com/sferik/twitter.git
2. cd twitter
3. gem install bundler
4. bundle install
5. bundle exec rake spec

468 specs will fail with an error message similar to:

NoMethodError:
  protected method `params' called for #<HTTP::Options:0x8badf00d>

On all supported versions of CRuby, these specs all pass. These specs also pass on JRuby 1.7.21 and JRuby 9.0.0.0 up to the pre2 release, so this regression must have been introduced some time between pre1 and pre2, which narrows it down to just 2,852 commits. 😉

I hope helps you to identify and fix this issue before the JRuby 9.0.0.0 final release. Sorry for not testing sooner.

FWIW, most of the other gems I’ve tests pass with flying colors on JRuby 9.0.0.0.rc2.