code: function Polygon(polygon) {
          crs(polygon);
          bbox(polygon);
          if (!requiredProperty(polygon, 'coordinates', 'array')) {
              if (!positionArray(polygon.coordinates, 'LinearRing', 2)) {
                  rightHandRule(polygon, errors);
              }
          }
      }
docs: https://tools.ietf.org/html/rfc7946#section-3.1.6