getClosestPoint(point, closestPoint) {
    closestPoint = closestPoint ? closestPoint : [NaN, NaN];
    this.closestPointXY(point[0], point[1], closestPoint, Infinity);
    return closestPoint;
  }
Return the closest point of the geometry to the passed point as
{@link module:ol/coordinate~Coordinate coordinate}.
@param {import("../coordinate.js").Coordinate} point Point.
@param {import("../coordinate.js").Coordinate} [closestPoint] Closest point.
@return {import("../coordinate.js").Coordinate} Closest point.
@api