static boolean extractHasGroupFromKey(long key) {
    return (key & 1) == 1;
  }
Encode key by {@code tile} asc, {@code layer} asc, {@code sortKey} asc with an extra bit to indicate whether the
value contains grouping information.
planetiler-core/src/main/java/com/onthegomap/planetiler/collection/FeatureGroup.java