public final Geometry centroidIfConvex() throws GeometryException {
    return centroidIfConvex != null ? centroidIfConvex : (centroidIfConvex = computeCentroidIfConvex());
  }
Returns and caches a point inside the geometry in world web mercator coordinates.
<p>
If the geometry is convex, uses the faster {@link Geometry#getCentroid()} but otherwise falls back to the slower
{@link Geometry#getInteriorPoint()}.
planetiler-core/src/main/java/com/onthegomap/planetiler/geo/WithGeometry.java