public double area() throws GeometryException {
    return Double.isNaN(area) ? (area = canBePolygon() ? Math.abs(polygon().getArea()) : 0) : area;
  }
Returns and caches the result of {@link Geometry#getArea()} of this feature in world web mercator coordinates where
{@code 1} means the area of the entire planet.
planetiler-core/src/main/java/com/onthegomap/planetiler/geo/WithGeometry.java