title: CollectionAssert.AreEqual fails when compare list return form wcf service
body: <p>below code fails because object in actual collection has ExtensionData field is "System.Runtime.Serialization.ExtensionDataObject" but object in expected list is null. is that possible skip test this field? </p>
  
  <pre><code>var expected = new List(&lt;ServiceReference1.Order&gt;)();
  var client = ServiceReference1.OrderServiceClient();
  var actual = client.GetOrder();
  CollectionAssert.AreEqual(expected, actual);
  </code></pre>