// TODO: Remove if not needed
        //[Test]
        public void Test_AddLink_TwoWay_SingleEntity()
        {
            var invoice = new ExampleInvoice ();
            var invoiceItem = new ExampleInvoiceItem ();

            var adder = new EntityLinker ();

            adder.AddLink (invoice, "Right", invoiceItem);

            Assert.IsNotNull (invoice.Items, "Link failed.");
            Assert.AreEqual(1, invoice.Items.Length, "Link failed.");
            Assert.IsNotNull (invoiceItem.Invoice, "Reverse link failed.");
        }
        public ExampleInvoiceItem(ExampleInvoice invoice)
        {
            Invoice = invoice;

            invoice.Add (this);
        }