getExtent(extent) {
    if (this.extentRevision_ != this.getRevision()) {
      const extent = this.computeExtent(this.extent_);
      if (isNaN(extent[0]) || isNaN(extent[1])) {
        createOrUpdateEmpty(extent);
      }
      this.extentRevision_ = this.getRevision();
    }
    return returnOrUpdate(this.extent_, extent);
  }
Get the extent of the geometry.
@param {import("../extent.js").Extent} [extent] Extent.
@return {import("../extent.js").Extent} extent Extent.
@api