||This abstract class is a partial implementation of the abstract class Preferences, which can be used to simplify
Preferences provider's implementation.
||This is the event class to indicate that one child of the preference node has been added or deleted.
||This is the event class to indicate that a preference has been added, deleted or updated.
||An instance of the class
Preferences represents one node in a preference tree, which provides a mechanism to store and access configuration data in a hierarchical way.