factory.addFunction(new GeometrySymDifference());
factory.addFunction(new GeometryBoundary());
factory.addFunction(new GeometryCentroid());
factory.addFunction(new GeometryConvexHull());
factory.addFunction(new ConvertToMetre());
factory.addFunction(new ConvertToSquareMetre());
String bagPrefix = "urn:ogc:def:function:geoxacml:1.0:geometry";
String functionName;