Solution to 236b: Fields for properties
See code at solutions/code/tutorialquestions/question236b
The key point here is that all of these fields are relevant
to all types of property, thus they should belong in the abstract Property superclass.
If you used a Property interface, rather than an abstract class, then you may need to adapt
your design a bit to allow these fields to be represented at an abstract level.
In the sample solution I have simply redefined Property, providing it with the new fields
with protected visibility (so that these fields are visible to subclasses of Property).