Adding employee and employee test.
Adding item and item test.
Adding fine receipt and fine receipt test.
Adding usage (test should be similar, not adding here).
Adding inexact payment exception.
Adding item unavailable exception.
Adding payment based on usage.
Adding reservation.
Adding room:
- room feature.
- room scenario test.
- room UML class diagram (requires ObjectAid, see link below).

Details: http://fuzz-box.blogspot.dk/2012/09/how-to-generate-uml-diagrams-from-java.html