applyTransform(transformFn) {
    const geometries = this.geometries_;
    for (let i = 0, ii = geometries.length; i < ii; ++i) {
      geometries[i].applyTransform(transformFn);
    }
    this.changed();
  }
Apply a transform function to the coordinates of the geometry.
The geometry is modified in place.
If you do not want the geometry modified in place, first `clone()` it and
then use this function on the clone.
@param {import("../proj.js").TransformFunction} transformFn Transform function.
Called with a flat array of geometry coordinates.
@api
@override