public TrackType TrackType {get;}

{
  //spatial or non-spatial?
  if (streamLayer.TrackType == TrackType.AttributeOnly)
  {
    //this is a non-spatial stream layer
  }
  else
  {
    //this must be a spatial stream layer
  }
}

{
  var trackType = streamLayer.TrackType;
  switch (trackType)
  {
    //TODO deal with tracktype
    case TrackType.None:
    case TrackType.AttributeOnly:
    case TrackType.Spatial:
      break;
  }
}

{
  //The layer must be track aware and spatial
  if (streamLayer.TrackType != TrackType.Spatial)
  {
    // not track aware and spatial
  }
  // Note: call within QueuedTask.Run()
  {
    //get the CIM Definition
    var def = streamLayer.GetDefinition() as CIMFeatureLayer;
    //set the number of previous observations, 
    def.PreviousObservationsCount = (int)streamLayer.GetExpirationMaxCount() - 1;
    //set show previous observations and track lines to true
    def.ShowPreviousObservations = true;
    def.ShowTracks = true;
    //commit the changes
    streamLayer.SetDefinition(def);
  }
}