public DefinitionQuery DefinitionQuery {get; set;}

var flyrCreatnParam = new FeatureLayerCreationParams(new Uri(@"c:\data\world.gdb\cities"))
{
  Name = "World Cities",
  IsVisible = false,
  MinimumScale = 1000000,
  MaximumScale = 5000,
  // At 2.x - DefinitionFilter = new CIMDefinitionFilter()
  //{
  //  DefinitionExpression = "Population > 100000",
  //  Name = "More than 100k"
  //},
  DefinitionQuery = new DefinitionQuery(whereClause: "Population > 100000", name: "More than 100k"),
  RendererDefinition = new SimpleRendererDefinition()
  {
    SymbolTemplate = SymbolFactory.Instance.ConstructPointSymbol(
      CIMColor.CreateRGBColor(255, 0, 0), 8, SimpleMarkerStyle.Hexagon).MakeSymbolReference()
  }
};

var featureLayer = LayerFactory.Instance.CreateLayer<FeatureLayer>(
  flyrCreatnParam, map);

//The catalog path of the feature layer to add to the map
var featureClassUriDefinition = new Uri(@"C:\Data\Admin\AdminData.gdb\USA\cities");
//Define the Feature Layer's parameters.
//At 2.x - var layerParamsQueryDefn = new FeatureLayerCreationParams(featureClassUriDefinition)
//{
//  IsVisible = true,
//  DefinitionFilter = new CIMDefinitionFilter()
//  {
//    Name = "CACities",
//    DefinitionExpression = "STATE_NAME = 'California'"
//  }
//};
var layerParamsQueryDefn = new FeatureLayerCreationParams(featureClassUriDefinition)
{
  IsVisible = true,
  DefinitionQuery = new DefinitionQuery(whereClause: "STATE_NAME = 'California'", name: "CACities")
};

//Create the layer with the feature layer parameters and add it to the active map
var createdFCWithQueryDefn = LayerFactory.Instance.CreateLayer<FeatureLayer>(layerParamsQueryDefn, MapView.Active.Map);

//Must be on the QueuedTask
var url = "https://geoeventsample1.esri.com:6443/arcgis/rest/services/AirportTraffics/StreamServer";
var lyrCreateParam = new FeatureLayerCreationParams(new Uri(url))
{
  IsVisible = true,
  //At 2.x - DefinitionFilter = new CIMDefinitionFilter()
  //{
  //  DefinitionExpression = "RWY = '29L'",
  //  Name = "Runway"
  //}
  DefinitionQuery = new DefinitionQuery(whereClause: "RWY = '29L'", name: "Runway")
};

var streamLayer = LayerFactory.Instance.CreateLayer<StreamLayer>(lyrCreateParam, map);