ClassValue rooting objects after it goes away?

[Charles Oliver Nutter]

Pardon me if this has been discussed before, but we had a bug (with
fix) reported today that seems to indicate that the JVM is rooting
objects put into a ClassValue even if the ClassValue goes away.

Here's the pull request: https://github.com/jruby/jruby/pull/3228

And here's one example of the root trace leading back to our JRuby
runtime. All the roots appear to be VM-level code:

https://dl.dropboxusercontent.com/u/9213410/class-values-leak.png

Is this expected? If we have to stuff a WeakReference into the
ClassValue it seriously diminishes its utility to us.

- Charlie