This bug will track all rubygems reviews, which depend on Java packages. Some bugs do not have correct or any Java package name, because there is needed opinion from advanced Java packager.
Currently, Google Closure Compiler  and YUI Compressor  are required.
The yui-compressor is required in version 2.4.4 and the Closure Compiler originally uses jar as of 2011-03-22. I guess both libraries could be used in newer versions if their command line parameters are backward compatible.
I recommend we simply require Closure Compiler to replace requires of yui-compressor. Closure Compiler states they are backwards compatible from a CLI point of view. This may simplify things.
So after reviewing closure compiler build/sources I have come to this:
compiler has non-trivial dependencies and considering how small the package is, it's one of the ugliest beasts I've ever seen (and I've seen quite a few ugly ones).
A list of issues that will make it hard to get it to Fedora/RHEL:
1. It needs guava r09 which in turn needs openjdk 1.7.0 to compile (sun jdk 1.6.0 works fine, it's a bug in 1.6.0 openjdk javac, but still...).
2. It needs gwt - Google Web Toolkit. I know there are people working on getting it to Fedora right now, but it's non-trivial task.
I'll look into it more but I am really not a fan of Google java libraries (almost all of them contain these bundled traps).
Ah, sorry taking point 2 back. It's actually guava r09 that can build additional targets if gwt is available (not required though). Guava can be updated in F17+ without problems because we have openjdk 1.7.0 there. So in the end it's rhino bundling and relocation that's the biggest issue
I took a look at yuicompressor as well and the situation is somewhat better than closure-compiler.
Current release has modified Rhino 1.7R2 sources, but they are limited to 4 changed source files and package name stays the same so it causes less problems for us. There is an upstream bug  for updating rhino dependency to 1.7R3, which includes most of the rhino changes needed so only 1 changed source file is left. This still causes bundling clause of packaging guidelines to come into play though. So what we need is to merge needed changes to Rhino 1.7R4 (if there ever is one) and use latest yuicompressor.
That said, I still believe yuicompressor is a better choice from closure-compiler. If nothing else, it seems to be playing nicer with Rhino upstream which will matter to us in long-term.
This bug appears to have been reported against 'rawhide' during the Fedora 19 development cycle.
Changing version to '19'.
(As we did not run this process for some time, it could affect also pre-Fedora 19 development
cycle bugs. We are very sorry. It will help us with cleanup during Fedora 19 End Of Life. Thank you.)
More information and reason for this action is here:
Imho not needed anymore.