Tidy up Package and classloader comments

After commit 31ae6d22605a0967d722f935bc3a8b868ada4917

Remove a TODO, improve a test and fix a comment.
Also fixes a bug in Package demonstrated by the improved test.

Bug: 20482259
Change-Id: I6b37413d7004ce85c99bb854e0ec41e5f8588250
6 files changed