public CIMSymbolReference SymbolTemplate {get; set;}

{
  // Note: call within QueuedTask.Run()
  {
    streamLayer = null;
    //https://geoeventsample1.esri.com:6443/arcgis/rest/services/AirportTraffics/StreamServer

    var uvrDef = new UniqueValueRendererDefinition()
    {
      ValueFields = new List<string> { "ACTYPE" },
      SymbolTemplate = SymbolFactory.Instance.ConstructPointSymbol(
        ColorFactory.Instance.RedRGB, 10, SimpleMarkerStyle.Hexagon)
          .MakeSymbolReference(),
      ValuesLimit = 5
    };
    //Note: CreateRenderer can only create value classes based on
    //the current events it has received
    streamLayer.SetRenderer(streamLayer.CreateRenderer(uvrDef));
  }
}