private async void OrderList_OnItemSelected(object sender, SelectedItemChangedEventArgs e)
{
if (e.SelectedItem == null)
{
return;
}
var selectedItem = e.SelectedItem as OrderItemViewModel;
var orderDetailVm = await vm.GetViewModelForOrderDetail(selectedItem);
await Navigation.PushAsync(new OrderDetailsPage(orderDetailVm), true);
}