public override async void OnNavigatedTo(NavigatedToEventArgs e, Dictionary <string, object> viewModelState)
        {
            base.OnNavigatedTo(e, viewModelState);

            Contacts       = null;
            _contactsCount = await OfficeService.GetContactsCount();
            await GetFirstPage();
        }
        private async void OnInitialize(object parameter)
        {
            GetEvent <InitDialogEvent>().Unsubscribe(OnInitialize);

            Contacts       = null;
            _contactsCount = await OfficeService.GetContactsCount();
            await GetFirstPage();
        }