public class CIMHatchFill : CIMFill, System.ComponentModel.INotifyPropertyChanged, System.Xml.Serialization.IXmlSerializable  

/// <summary>
/// Create a polygon symbol with a diagonal cross hatch fill. <br/>
/// ![PolygonSymbolDiagonalCrossHatch](http://Esri.github.io/arcgis-pro-sdk/images/Symbology/polygon-diagonal-crosshatch.png)
/// </summary>
/// <returns></returns>
public static Task<CIMPolygonSymbol> CreateDiagonalCrossPolygonAsync()
{
  return QueuedTask.Run<CIMPolygonSymbol>(() =>
  {
    var trans = 50.0;//semi transparent
    CIMStroke outline = SymbolFactory.Instance.ConstructStroke(CIMColor.CreateRGBColor(0, 0, 0, trans), 2.0, SimpleLineStyle.Solid);

    //Stroke for the fill
    var solid = SymbolFactory.Instance.ConstructStroke(CIMColor.CreateRGBColor(255, 0, 0, trans), 1.0, SimpleLineStyle.Solid);

    //Mimic cross hatch
    CIMFill[] diagonalCross =
              {
                new CIMHatchFill() {
                    Enable = true,
                    Rotation = 45.0,
                    Separation = 5.0,
                    LineSymbol = new CIMLineSymbol() { SymbolLayers = new CIMSymbolLayer[1] { solid } }
                },
                new CIMHatchFill() {
                    Enable = true,
                    Rotation = -45.0,
                    Separation = 5.0,
                    LineSymbol = new CIMLineSymbol() { SymbolLayers = new CIMSymbolLayer[1] { solid } }
                }
      };
    List<CIMSymbolLayer> symbolLayers = new List<CIMSymbolLayer>
      {
                outline
      };
    foreach (var fill in diagonalCross)
      symbolLayers.Add(fill);
    return new CIMPolygonSymbol() { SymbolLayers = symbolLayers.ToArray() };
  });
}