title: Serialized XML Date Time value is not correct
body: <p>I have an issue with Serializing XML. I have an object with a DateTime property where the millisecond value is 990. However when I view the outputted string it is showing like this...</p>
  
  <pre><code>&lt;ReadingsDateTime&gt;2016-07-04T10:10:00.99Z&lt;/ReadingsDateTime&gt;
  </code></pre>
  
  <p>The code used to convert this to xml is below, what is going on, I can not find a reason that this is happening.</p>
  
  <pre><code>string xml;
  
  try
  {    
      var serializer = new XmlSerializerFactory().CreateSerializer(typeof(T), xmlNamespace);
  
      using (var memoryStream = new MemoryStream())
      {
          var settings = new XmlWriterSettings
          {
              Indent = false,
              NamespaceHandling = NamespaceHandling.OmitDuplicates,
              CloseOutput = false,
              WriteEndDocumentOnClose = true,
          };
  
          using (var xmlWriter = XmlWriter.Create(memoryStream, settings))
          {
              serializer?.Serialize(xmlWriter, obj);
          }
  
          memoryStream.Seek(0, SeekOrigin.Begin);
  
          using (var steamReader = new StreamReader(memoryStream))
          {
              xml = steamReader.ReadToEnd();
          }
      }
  }
  catch (Exception ex)
  {
      throw new ApplicationException("Unable to convert to XML from an object", ex);
  }
  
  return xml;
  </code></pre>