public class CIMStandardDataConnection : CIMDataConnection, System.ComponentModel.INotifyPropertyChanged, System.Xml.Serialization.IXmlSerializable  

{
    CIMStandardDataConnection cIMStandardDataConnection = new CIMStandardDataConnection()
    {
        WorkspaceConnectionString = @"SWAPXY=TRUE;SWAPXYFILTER=FALSE;URL=http://sampleserver6.arcgisonline.com/arcgis/services/SampleWorldCities/MapServer/WFSServer;VERSION=2.0.0",
        WorkspaceFactory = WorkspaceFactory.WFS,
        Dataset = "Continent",
        DatasetType = esriDatasetType.esriDTFeatureClass
    };

    // Add a new layer to the map
    var layerPamsDC = new LayerCreationParams(cIMStandardDataConnection);
    //Note: Needs QueuedTask to run
    Layer layerCreated = LayerFactory.Instance.CreateLayer<FeatureLayer>(layerPamsDC, MapView.Active.Map);
}

{
    CIMStandardDataConnection dataConnection = featureLayer.GetDataConnection() as CIMStandardDataConnection;
    dataConnection.WorkspaceConnectionString = @"DATABASE=C:\Data\USNationalParks\USNationalParks.gdb";
    //Note: needs to be called on the MCT
    featureLayer.SetDataConnection(dataConnection);
}