Type-safe enumerations that are used as property types that are editable with a PropertyEditor should implement this interface.
An icon can be provided that will be shown in a list
along with the textual description of the element.
This method should return null if there
is no icon available.
Type-safe Enumerations implementing this interface
should override the toString() method to return a
String that will be helpful to the user
when choosing this as an option from a list.