/// <summary>
 /// Gets the blip targeted by this operation, creating a data document if it does not exist.
 /// </summary>
 /// <param name="target"></param>
 /// <returns>blip targeted by this operation, never null</returns>
 private IBlipData GetTargetBlip(IWaveletData target)
 {
     return target.GetDocument(BlipId) 
         ?? target.CreateDocument(BlipId, Context.Creator,
             new Collection<ParticipantId> { Context.Creator }, 
             EmptyDocument.Empty,
             Context.Timestamp, target.Version + Context.VersionIncrement);            
 }