public JTSPointExpression<Point> pointOnSurface() {
        if (pointOnSurface == null) {
            pointOnSurface = JTSGeometryExpressions.pointOperation(SpatialOps.POINT_ON_SURFACE, mixin);
        }
        return pointOnSurface;
    }
A Point guaranteed to be on this Surface.

@return point on surface
querydsl-spatial/src/main/java/com/querydsl/spatial/jts/JTSSurfaceExpression.java