assertTrue(multimap.keySet() instanceof SortedSet);
    assertTrue(multimap.asMap() instanceof SortedMap);
  }

  public void testTreeKeys_gwtCompatible() {
    ListMultimap<String, Integer> multimap =
        rawtypeToWildcard(MultimapBuilder.treeKeys()).arrayListValues().<String, Integer>build();
    assertTrue(multimap.keySet() instanceof SortedSet);

    return Collections.unmodifiableSet(adjacentNodeValues.keySet());
  }

  @Override
  public Set<N> predecessors() {
    return adjacentNodes();
  }

  @Override
  public Set<N> successors() {
    return adjacentNodes();
  }

  @Override
  public Iterator<EndpointPair<N>> incidentEdgeIterator(N thisNode) {
    return Iterators.transform(
        adjacentNodeValues.keySet().iterator(),

    } catch (RuntimeException tolerated) {
      // GWT's HashMap.keySet().removeAll(null) doesn't throws NPE.
    }
  }

  @Override
  public void testKeySetRetainAllNullFromEmpty() {
    try {
      super.testKeySetRetainAllNullFromEmpty();
    } catch (RuntimeException tolerated) {
      // GWT's HashMap.keySet().retainAll(null) doesn't throws NPE.
    }
  }

  @Override

   */
  public static Set<Class<?>> allPrimitiveTypes() {
    return PRIMITIVE_TO_WRAPPER_TYPE.keySet();
  }

  /**
   * Returns an immutable set of all nine primitive-wrapper types (including {@link Void}).
   *
   * @since 3.0
   */
  public static Set<Class<?>> allWrapperTypes() {
    return WRAPPER_TO_PRIMITIVE_TYPE.keySet();
  }

  /**

    } catch (RuntimeException tolerated) {
      // GWT's TreeMap.keySet().removeAll(null) doesn't throws NPE.
    }
  }

  @Override
  public void testKeySetRetainAllNullFromEmpty() {
    try {
      super.testKeySetRetainAllNullFromEmpty();
    } catch (RuntimeException tolerated) {
      // GWT's TreeMap.keySet().retainAll(null) doesn't throws NPE.
    }
  }

  @Override

    checkNotNull(map); // GWT specific check (do not optimize)
    if (map.isEmpty()) {
      return EMPTY_REPLACEMENT_ARRAY;
    }
    char max = max(map.keySet());
    char[][] replacements = new char[max + 1][];
    for (Character c : map.keySet()) {
      replacements[c] = map.get(c).toCharArray();
    }
    return replacements;
  }

  // Immutable empty array for when there are no replacements.

    builder.put("c", 4);
    builder.put("a", 2);
    builder.put("b", 6);
    ImmutableListMultimap<String, Integer> multimap = builder.build();
    assertThat(multimap.keySet()).containsExactly("d", "c", "b", "a").inOrder();
    assertThat(multimap.values()).containsExactly(2, 4, 3, 6, 5, 2).inOrder();
    assertThat(multimap.get("a")).containsExactly(5, 2).inOrder();

    checkArgument(!delegate.isEmpty());
  }

  @Override
  UnmodifiableIterator<K> keyIterator() {
    return Iterators.unmodifiableIterator(delegate.keySet().iterator());
  }

  @Override
  Spliterator<K> keySpliterator() {
    return delegate.keySet().spliterator();
  }

  @Override
  public int size() {
    return delegate.size();
  }

  @Override

    cache.getUnchecked(one);
    Map<Object, Object> newMap = ImmutableMap.of(one, one);
    assertThat(map).isEqualTo(newMap);
    assertThat(map.entrySet()).isEqualTo(newMap.entrySet());
    assertThat(map.keySet()).isEqualTo(newMap.keySet());
    Set<Object> expectedValues = ImmutableSet.of(one);
    Set<Object> actualValues = ImmutableSet.copyOf(map.values());
    assertThat(actualValues).isEqualTo(expectedValues);
  }

    cache.getUnchecked(one);
    Map<Object, Object> newMap = ImmutableMap.of(one, one);
    assertThat(map).isEqualTo(newMap);
    assertThat(map.entrySet()).isEqualTo(newMap.entrySet());
    assertThat(map.keySet()).isEqualTo(newMap.keySet());
    Set<Object> expectedValues = ImmutableSet.of(one);
    Set<Object> actualValues = ImmutableSet.copyOf(map.values());
    assertThat(actualValues).isEqualTo(expectedValues);
  }