Is it possible to have an attached property that cast the type to the type that is needed in the view model?

Question

Until now, to can know in the view model the selected items in a list view, I am using an attached property.

This is the code:

public class ListViewSelectedItemsBehavior : Behavior<ListView>
{
    protected override void OnAttached()
    {
        AssociatedObject.SelectionChanged += AssociatedObjectSelectionChanged;
    }
    protected override void OnDetaching()
    {
        AssociatedObject.SelectionChanged -= AssociatedObjectSelectionChanged;
    }

    void AssociatedObjectSelectionChanged(object sender, SelectionChangedEventArgs e)
    {

        SelectedItems = new ObservableCollection<object>(AssociatedObject.SelectedItems.Cast<object>());
    }


    public ObservableCollection<object> SelectedItems
    {
        get { return (ObservableCollection<object>)GetValue(SelectedItemsProperty); }
        set { SetValue(SelectedItemsProperty, value); }
    }


    public static readonly DependencyProperty SelectedItemsProperty =
        DependencyProperty.Register("SelectedItems"
            , typeof(ObservableCollection<object>)
            , typeof(ListViewSelectedItemsBehavior)
            ,
        new FrameworkPropertyMetadata(null, FrameworkPropertyMetadataOptions.BindsTwoWayByDefault));
}

The problem is that the ObservableCollection is of type object, but in the view model I need to work with a collection of the specific type that it needs. So I have to do something like that in the view model:

partial void OnMyCollectionSelectedItemsChanged(ObservableCollection<object> value)
{
    _myCollectionSelectedItemsTyped!.Clear();
    if (value != null) _myCollectionSelectedItemsTyped.AddRange(value.Cast<string>());
}


private List<string> _myCollectionSelectedItemsTyped = new List<string>();

I was thinking that if in the attached property I could do in some way to use a generic type or another way to avoid to have to add this code in the view models, it would be a good improvement. But really I don't know how could I do it.

Thanks.