setId(id) {
    this.id_ = id;
    this.changed();
  }
Set the feature id.  The feature id is considered stable and may be used when
requesting features or comparing identifiers returned from a remote source.
The feature id can be used with the
{@link module:ol/source/Vector~VectorSource#getFeatureById} method.
@param {number|string|undefined} id The feature id.
@api
@fires module:ol/events/Event~BaseEvent#event:change