Sorry, I should have been more clear. I know that it is possible to load the resources directly from the jar files, I just don't how much work that is going to take. I agree that avoiding the unzipping of jar files into temp directories and having to manage those directories for deletion is the preferred solution.
Another thing I was thinking of and would like to get thoughts on is a convention versus configuration solution. Instead of browsing jar files for named resources, and then having to deal with the contention issues between directories and resources in jars being named the same, what if we were to have plugin jar files named a given way, something like name-plugin.jar. For example the prefix urlfilter plugin would be named urlfilter-prefix-plugin.jar. There would be a single plugin per jar and each jar would be the root directory for its plugin. Then to find plugin jars we are just scanning the classpath for certain named jars. The downside to this is we could end up with a lot of jars, but currently we are ending up with a lot of folders so I don't know if that is a big difference. Thoughts?