public < T > void addListItem ( PropertyListKey < T > property , T value ) { List < T > list = get ( property ) ; list . add ( value ) ; if ( ! contains ( property ) ) { set ( property , list ) ; } }
Append the value to the list to which the specified property key is mapped . If this properties contains no mapping for the property key the value append to a new list witch is associate the the specified property key .