if (collection instanceof NavigableSet) {
        return Sets.unmodifiableNavigableSet((NavigableSet<E>) collection);
      } else if (collection instanceof SortedSet) {
        return Collections.unmodifiableSortedSet((SortedSet<E>) collection);
      } else if (collection instanceof Set) {
        return Collections.unmodifiableSet((Set<E>) collection);
      } else if (collection instanceof List) {

      if (collection instanceof NavigableSet) {
        return Sets.unmodifiableNavigableSet((NavigableSet<E>) collection);
      } else if (collection instanceof SortedSet) {
        return Collections.unmodifiableSortedSet((SortedSet<E>) collection);
      } else if (collection instanceof Set) {
        return Collections.unmodifiableSet((Set<E>) collection);
      } else if (collection instanceof List) {

    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;
  }

  /**

      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;
  }

  /**

    private final SortedSet<E> unmodifiableDelegate;

    UnmodifiableNavigableSet(NavigableSet<E> delegate) {
      this.delegate = checkNotNull(delegate);
      this.unmodifiableDelegate = Collections.unmodifiableSortedSet(delegate);
    }

    @Override
    protected SortedSet<E> delegate() {
      return unmodifiableDelegate;
    }

    @Override
    public @Nullable E lower(@ParametricNullness E e) {

    private final SortedSet<E> unmodifiableDelegate;

    UnmodifiableNavigableSet(NavigableSet<E> delegate) {
      this.delegate = checkNotNull(delegate);
      this.unmodifiableDelegate = Collections.unmodifiableSortedSet(delegate);
    }

    @Override
    protected SortedSet<E> delegate() {
      return unmodifiableDelegate;
    }

    // default methods not forwarded by ForwardingSortedSet