private static void Assert_root_breadcrumb_values(Breadcrumb breadcrumb)
 {
     breadcrumb.ShouldNotBeNull();
     breadcrumb.DisplayString.ShouldBe("ROOT");
     breadcrumb.ItemTypesShouldBe<L0>();
     breadcrumb.Parent.ShouldBeNull();
     breadcrumb.Path.ShouldBeNull();
     breadcrumb.PropertiesShouldBeNull();
 }