new ImmutableSortedMap<>(ImmutableSortedSet.emptySet(Ordering.natural()), ImmutableList.of());

  static <K, V> ImmutableSortedMap<K, V> emptyMap(Comparator<? super K> comparator) {
    if (Ordering.natural().equals(comparator)) {
      return of();
    } else {
      return new ImmutableSortedMap<>(ImmutableSortedSet.emptySet(comparator), ImmutableList.of());
    }
  }

  /**

  // TreeSet

  /**
   * Creates a <i>mutable</i>, empty {@code TreeSet} instance sorted by the natural sort ordering of
   * its elements.
   *
   * <p><b>Note:</b> if mutability is not required, use {@link ImmutableSortedSet#of()} instead.
   *
   * <p><b>Note:</b> this method is now unnecessary and should be treated as deprecated. Instead,
   * use the {@code TreeSet} constructor directly, taking advantage of <a

        () -> map.headMap("r", false).tailMap("m", true).keySet().add("a"));
  }

  @GwtIncompatible // NavigableMap
  public void testAsMapNavigableEmpty() {
    NavigableSet<String> strings = ImmutableSortedSet.of();
    NavigableMap<String, Integer> map = Maps.asMap(strings, LENGTH_FUNCTION);
    assertThat(map.entrySet()).isEmpty();
    assertTrue(map.isEmpty());
    assertThat(map.get("five")).isNull();
  }

        () -> map.headMap("r", false).tailMap("m", true).keySet().add("a"));
  }

  @GwtIncompatible // NavigableMap
  public void testAsMapNavigableEmpty() {
    NavigableSet<String> strings = ImmutableSortedSet.of();
    NavigableMap<String, Integer> map = Maps.asMap(strings, LENGTH_FUNCTION);
    assertThat(map.entrySet()).isEmpty();
    assertTrue(map.isEmpty());
    assertThat(map.get("five")).isNull();
  }