setLayers(layers) {
    const collection = this.getLayers();
    if (collection) {
      const currentLayers = collection.getArray();
      for (let i = 0, ii = currentLayers.length; i < ii; ++i) {
        this.dispatchEvent(new GroupEvent('removelayer', currentLayers[i]));
      }
    }

    this.set(Property.LAYERS, layers);
  }
Set the {@link module:ol/Collection~Collection collection} of {@link module:ol/layer/Layer~Layer layers}
in this group.
@param {!Collection<import("./Base.js").default>} layers Collection of
  {@link module:ol/layer/Base~BaseLayer layers} that are part of this group.
@observable
@api