public final Geometry pointOnSurface() throws GeometryException {
    return pointOnSurface != null ? pointOnSurface : (pointOnSurface =
      canBePolygon() ? polygon().getInteriorPoint() :
        canBeLine() ? line().getInteriorPoint() :
        worldGeometry().getInteriorPoint());
  }
Returns and caches {@link Geometry#getInteriorPoint()} of this geometry in world web mercator coordinates.
planetiler-core/src/main/java/com/onthegomap/planetiler/geo/WithGeometry.java