/// <summary>
 /// Checks the given activity for new parties and adds them to the collection, if not
 /// already there.
 /// </summary>
 /// <param name="activity">The activity.</param>
 public void MakeSurePartiesAreTracked(IActivity activity)
 {
     MakeSurePartiesAreTracked(
         MessagingUtils.CreateSenderParty(activity),
         MessagingUtils.CreateRecipientParty(activity));
 }