anchor.diff:                  let affinity = tryGet Settings.AffinityProperty
                   let deliveryCount = message.DeliveryCount
                   let parentId = fromGuid (message.Properties.[Settings.ParentTaskIdProperty] :?> Guid)
  -                let streamPos = tryGet Settings.StreamOffsetProperty
  +                let batchIndex = tryGet Settings.BatchIndexProperty
                   let lockToken = message.LockToken
                   let body = fromGuid (message.GetBody<Guid>())
                   let jobId = message.Properties.[Settings.JobIdProperty] :?> Guid
  
positive.code:         ContentId : string
          MessageLockId : Guid
          ParentJobId : string
          Offset : int64 option 
          TargetWorker : string option
          DeliveryCount : int
          DequeueTime : DateTimeOffset
  
negative.code:     static member AffinityProperty = "worker"
      /// ParentTaskId.
      static member ParentTaskIdProperty = "parentId"
      /// BatchIndex.
      static member BatchIndexProperty = "batchIndex"
      /// JobId.
      static member JobIdProperty = "uuid"
      /// SUbscription queue auto delete interval.
  