/// <summary>
 /// Applies this <see cref="TrackingContext"/> instance to the <paramref name="targetMessage"/>.
 /// </summary>
 /// <param name="targetMessage">
 /// Message to contain the tracking information.
 /// </param>
 public void Apply(XLANGMessage targetMessage)
 {
     if (targetMessage == null)
     {
         throw new ArgumentNullException("targetMessage");
     }
     targetMessage.SetTrackingContext(this);
 }