presto-geospatial/src/main/java/io/prestosql/plugin/geospatial/GeoFunctions.java/GeoFunctions/getPolygonSansHolesCentroid
class GeoFunctions:    private static Point getPolygonSansHolesCentroid(Polygon polygon)
    {
        int pointCount = polygon.getPointCount();
        double xSum = 0;
        double ySum = 0;
        double signedArea = 0;
        for (int i = 0; i < pointCount; i++) {
            Point current = polygon.getPoint(i);
            Point next = polygon.getPoint((i + 1) % polygon.getPointCount());
            double ladder = current.getX() * next.getY() - next.getX() * current.getY();
            xSum += (current.getX() + next.getX()) * ladder;
            ySum += (current.getY() + next.getY()) * ladder;
            signedArea += ladder / 2;
        }
        return new Point(xSum / (signedArea * 6), ySum / (signedArea * 6));
    }