static long encodeKey(int tile, byte layer, int sortKey, boolean hasGroup) {
    return ((long) tile << 32L) | ((long) (layer & 0xff) << 24L) | (((sortKey - SORT_KEY_MIN) & SORT_KEY_MASK) << 1L) |
      (hasGroup ? 1 : 0);
  }
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