private static void OnForeignKeyConfigurationChanged(DependencyObject sender, DependencyPropertyChangedEventArgs e)
        {
            ForeignKeyContentControl contentControl = sender as ForeignKeyContentControl;

            if (contentControl != null)
            {
                contentControl.NotifyKeyChanged();
            }
        }
        private static void OnValueChanged(DependencyObject o, DependencyPropertyChangedEventArgs e)
        {
            ForeignKeyContentControl contentControl = o as ForeignKeyContentControl;

            if (contentControl != null)
            {
                contentControl.NotifyValueChanged();
            }
        }