constructor(center, radius, layout) {
    super();
    if (layout !== undefined && radius === undefined) {
      this.setFlatCoordinates(layout, center);
    } else {
      radius = radius ? radius : 0;
      this.setCenterAndRadius(center, radius, layout);
    }
  }
@param {!import("../coordinate.js").Coordinate} center Center.
    For internal use, flat coordinates in combination with `layout` and no
    `radius` are also accepted.
@param {number} [radius] Radius in units of the projection.
@param {import("./Geometry.js").GeometryLayout} [layout] Layout.