docs: private static boolean isLinearRing(LineString lineString) {
      if (lineString.coordinates().size() < 4) {
        throw new GeoJsonException("LinearRings need to be made up of 4 or more coordinates.");
      }
      if (!(lineString.coordinates().get(0).equals(
        lineString.coordinates().get(lineString.coordinates().size() - 1)))) {
        throw new GeoJsonException("LinearRings require first and last coordinate to be identical.");
      }
      return true;
    }