The "problems" and "solutions" present examples of the SOLID principles, plus DRY (don't repeat yourself).

The "gilded rose" presented here is one potential post-refactor solution.  It is the solution we developed at the OJUG meeting.
The "gilded rose" package also includes some additional test cases over the original and some code removed over the original.
Original "gilded rose" code found at:  https://github.com/alexaitken/GildedRose_java/blob/master/src/com/alexaitken/gildedrose