MapPoint Centroid( 
   Geometry geometry
)

{
  // simple polygon
  List<Coordinate2D> list2D =
  [
    new Coordinate2D(0, 0),
    new Coordinate2D(0, 2),
    new Coordinate2D(2, 2),
    new Coordinate2D(2, 0),
  ];

  polygon = PolygonBuilderEx.CreatePolygon(list2D, SpatialReferences.WGS84);

  // verify it is simple
  bool isSimple = GeometryEngine.Instance.IsSimpleAsFeature(polygon);
  // find the centroid
  MapPoint centroid = GeometryEngine.Instance.Centroid(polygon);
  // centroid.X = 1
  // centroid.Y = 1

  // map Point
  MapPoint pt1 = MapPointBuilderEx.CreateMapPoint(1, 2, 3, 4, SpatialReferences.WGS84);
  MapPoint pt2 = MapPointBuilderEx.CreateMapPoint(5, 2, double.NaN, 7);

  // pt1.HasZ = true
  // pt1.HasM = true
  centroid = GeometryEngine.Instance.Centroid(pt1);
  // centroid.HasZ = true
  // centroid.HasM = true
  // pt1.IsEqual(centroid) = true

  // multipoint
  List<MapPoint> list = [pt1, pt2];
  Multipoint multipoint = MultipointBuilderEx.CreateMultipoint(list);
  // multipoint.HasZ = true
  // multipoint.HasM = true

  centroid = GeometryEngine.Instance.Centroid(multipoint);
  // centroid.X = 3
  // centroid.Y = 2
  // centroid.HasZ = false
  // centroid.HasM = false
}