I have a gem with a C extension and java extension which installs fine in JRuby via rbenv, but fails to install in JRuby via RVM. The gemspec and project are on Github. I have tried explicitly listing the files in the gemspec, excluding the extconf.rb and *.c files when the platform is Java, but still cannot install the gem on RVM's JRuby.
You can try installing with gem install pg_array_parser --pre
to see the installation fail with the current gemspec in master. I'm not sure what else I can try at this point.