Adds a listener for before map entries are created, deleted, or updated.
See addMapChangeListener for the mechanics of this method, assuming that the beforeChange argument is true.
Adds a listener for when the value for a key changes, or when entries are added or removed.
Unregisters a map change listener provided by addBeforeMapChangeListener or addMapChangeListener with the beforeChange flag.
Informs map change listeners that an entry will be created, deleted, or updated.