}
  }

  private final transient RegularImmutableSortedSet<K> keySet;
  private final transient ImmutableList<V> valueList;
  private final transient @Nullable ImmutableSortedMap<K, V> descendingMap;

  ImmutableSortedMap(RegularImmutableSortedSet<K> keySet, ImmutableList<V> valueList) {
    this(keySet, valueList, null);
  }

  ImmutableSortedMap(
      RegularImmutableSortedSet<K> keySet,
      ImmutableList<V> valueList,