private final SortedSet<String> delegate = Sets.newTreeSet();

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

  public void testAsMapSorted() {
    SortedSet<String> strings = new NonNavigableSortedSet();
    Collections.addAll(strings, "one", "two", "three");
    SortedMap<String, Integer> map = Maps.asMap(strings, LENGTH_FUNCTION);