assertEquals(
        Collections.reverseOrder(), ((ImmutableSortedSet<Integer>) multimap.get("x")).comparator());
    assertTrue(multimap.asMap().get("a") instanceof ImmutableSortedSet);
    assertEquals(
        Collections.reverseOrder(),
        ((ImmutableSortedSet<Integer>) multimap.asMap().get("a")).comparator());
  }

  public void testBuilderOrderKeysAndValuesBy() {

      return asMap(backingSet().subSet(fromKey, toKey), function);
    }

    @Override
    public SortedMap<K, V> headMap(@ParametricNullness K toKey) {
      return asMap(backingSet().headSet(toKey), function);
    }

    @Override
    public SortedMap<K, V> tailMap(@ParametricNullness K fromKey) {
      return asMap(backingSet().tailSet(fromKey), function);
    }

      return asMap(backingSet().subSet(fromKey, toKey), function);
    }

    @Override
    public SortedMap<K, V> headMap(@ParametricNullness K toKey) {
      return asMap(backingSet().headSet(toKey), function);
    }

    @Override
    public SortedMap<K, V> tailMap(@ParametricNullness K fromKey) {
      return asMap(backingSet().tailSet(fromKey), function);
    }

   * access. Access time is reset by all cache read and write operations (including {@code
   * Cache.asMap().get(Object)} and {@code Cache.asMap().put(K, V)}), but not by {@code
   * containsKey(Object)}, nor by operations on the collection-views of {@link Cache#asMap}}. So,
   * for example, iterating through {@code Cache.asMap().entrySet()} does not reset access time for
   * the entries you retrieve.
   *

    cache.asMap().put(extraKey, extraKey);
    assertThat(cache.asMap().get(extraKey)).isSameInstanceAs(extraKey);

    Object[] lookupKeys = new Object[] {new Object(), new Object(), new Object()};
    assertThrows(InvalidCacheLoadException.class, () -> cache.getAll(asList(lookupKeys)));

    for (Object key : lookupKeys) {
      assertThat(cache.asMap().containsKey(key)).isTrue();
    }

  }

  @Override
  public CacheStats stats() {
    throw new UnsupportedOperationException();
  }

  @Override
  @J2ktIncompatible // Thread safety complexity
  public ConcurrentMap<K, V> asMap() {
    throw new UnsupportedOperationException();
  }

  /**
   * Accumulates statistics during the operation of a {@link Cache} for presentation by {@link

    cache.asMap().put(extraKey, extraKey);
    assertThat(cache.asMap().get(extraKey)).isSameInstanceAs(extraKey);

    Object[] lookupKeys = new Object[] {new Object(), new Object(), new Object()};
    assertThrows(InvalidCacheLoadException.class, () -> cache.getAll(asList(lookupKeys)));

    for (Object key : lookupKeys) {
      assertThat(cache.asMap().containsKey(key)).isTrue();
    }

   * {@code ConcurrentMap} documentation. They will not function correctly and it is impossible for
   * Guava to fix them until Guava is ready to <i>require</i> Java 8 for all users.
   */
  ConcurrentMap<K, V> asMap();

  /**
   * Performs any pending maintenance operations needed by the cache. Exactly which activities are
   * performed -- if any -- is implementation-dependent.
   */
  void cleanUp();

    @CanIgnoreReturnValue
    @Override
    public Builder<K, V> putAll(Multimap<? extends K, ? extends V> multimap) {
      for (Entry<? extends K, ? extends Collection<? extends V>> entry :
          multimap.asMap().entrySet()) {
        putAll(entry.getKey(), entry.getValue());
      }
      return this;
    }

    @CanIgnoreReturnValue
    @Override
    Builder<K, V> combine(ImmutableMultimap.Builder<K, V> other) {

    }

    // Each of the values added to the map should either still be there, or have seen a removal
    // notification.
    assertThat(Sets.union(cache.asMap().keySet(), removalNotifications.keySet()))
        .isEqualTo(expectedKeys);
    assertThat(cache.asMap().keySet()).containsNoneIn(removalNotifications.keySet());
    threadPool.shutdown();
    threadPool.awaitTermination(300, SECONDS);
  }

  /**