private void RoundTrip(CollectionMemento memento) {
            string[] strings1 = memento.ToEncodedStrings();
            var newMemento = new CollectionMemento(NakedObjectsFramework.LifecycleManager, NakedObjectsFramework.NakedObjectManager, NakedObjectsFramework.MetamodelManager, strings1);
            string[] strings2 = newMemento.ToEncodedStrings();
            Assert.IsTrue(strings1.SequenceEqual(strings2), "memento failed roundtrip");

            var copyMemento = new CollectionMemento(NakedObjectsFramework.LifecycleManager, NakedObjectsFramework.NakedObjectManager, NakedObjectsFramework.MetamodelManager, memento, new object[] {});
            string[] strings3 = copyMemento.ToEncodedStrings();
            Assert.IsTrue(strings1.SequenceEqual(strings3), "memento failed copy");
        }