this(Sets.newTreeSet(comparator));
  }

  ImmutableSortedSet(SortedSet<E> sortedDelegate) {
    super(sortedDelegate);
    this.sortedDelegate = Collections.unmodifiableSortedSet(sortedDelegate);
  }

  @Override
  public Comparator<? super E> comparator() {
    return sortedDelegate.comparator();
  }

      return unmodifiableSortedMap(
          Maps.transformValues(delegate().rowMap(), Collections::unmodifiableMap));
    }

    @Override
    public SortedSet<R> rowKeySet() {
      return Collections.unmodifiableSortedSet(delegate().rowKeySet());
    }

    @GwtIncompatible @J2ktIncompatible private static final long serialVersionUID = 0;
  }

  /**