handleDraggerEnd_(event) {
    if (this.dragging_) {
      const view = this.getMap().getView();
      view.endInteraction();

      this.dragging_ = false;
      this.startX_ = undefined;
      this.startY_ = undefined;
      this.dragListenerKeys_.forEach(unlistenByKey);
      this.dragListenerKeys_.length = 0;
    }
  }
Handle dragger end events.
@param {PointerEvent} event The drag event.
@private