onUserTagClick doesnt exist

[alfaruqrizqi18]

How to use this function? I didn't find it. I use latest version

onUserTagClick: (tag){
      _scaffoldKey.currentState.showSnackBar(
        SnackBar(
          content: ListTile(
            title: Text('User tag clicked!'),
            subtitle: Text(tag),
          ),
        ),
      );
    }