@SuppressWarnings("unchecked")
  static <T extends @Nullable Object> UnmodifiableListIterator<T> emptyListIterator() {
    return (UnmodifiableListIterator<T>) ArrayItr.EMPTY;
  }

  /**
   * This is an enum singleton rather than an anonymous class so ProGuard can figure out it's only
   * referenced by emptyModifiableIterator().
   */
  private enum EmptyModifiableIterator implements Iterator<Object> {
    INSTANCE;

    @Override

  private TimeUnit recordedTimeUnit;

  private final ListeningExecutorService executorService = new FakeExecutorService();

  public void testInvokeAny() throws Exception {
    Set<Callable<String>> tasks = Collections.singleton(() -> "invokeAny");

    String result = executorService.invokeAny(tasks, Duration.ofSeconds(7));

    assertThat(result).isEqualTo("invokeAny");
    assertThat(recordedTasks).isSameInstanceAs(tasks);

    return CollectCollectors.flatteningToImmutableSetMultimap(keyFunction, valuesFunction);
  }

  /**
   * Returns the empty multimap.
   *
   * <p><b>Performance note:</b> the instance returned is a singleton.
   */
  // Casting is safe because the multimap will never hold any elements.
  @SuppressWarnings("unchecked")
  public static <K, V> ImmutableSetMultimap<K, V> of() {

    return CollectCollectors.toImmutableBiMap(keyFunction, valueFunction);
  }

  /**
   * Returns the empty bimap.
   *
   * <p><b>Performance note:</b> the instance returned is a singleton.
   */
  // Casting to any type is safe because the set will never hold any elements.
  @SuppressWarnings("unchecked")
  public static <K, V> ImmutableBiMap<K, V> of() {

<components namespace="fessCrawler">
	<include path="crawler/container.xml" />

	<component name="mimeTypeHelper"
		class="org.codelibs.fess.crawler.helper.impl.MimeTypeHelperImpl" instance="singleton">
	</component>

	"http://dbflute.org/meta/lastadi10.dtd">
<components namespace="fessCrawler">
	<include path="crawler/container.xml" />

	<component name="sitemapsHelper" class="org.codelibs.fess.crawler.helper.SitemapsHelper"
		instance="singleton">
	</component>

                CollectionFeature.ALLOWS_NULL_QUERIES)
            .createTestSuite());

    suite.addTestSuite(ImmutableSortedSetTest.class);

    return suite;
  }

  // enum singleton pattern
  private enum StringLengthComparator implements Comparator<String> {
    INSTANCE;

    @Override
    public int compare(String a, String b) {
      return a.length() - b.length();
    }
  }

  /**
   * Returns an {@link OutputStream} that simply discards written bytes.
   *
   * <p><b>Java 11+ users:</b> use {@link OutputStream#nullOutputStream()} instead. Note that the
   * {@link ByteStreams} method returns a singleton stream whose {@code close} method has no effect,
   * while the {@link OutputStream} method returns a new instance whose {@code write} methods throw
   * if called on a closed stream.
   *

      return new RegularImmutableSortedSet<>(ImmutableList.of(), comparator);
    }
  }

  /**
   * Returns the empty immutable sorted set.
   *
   * <p><b>Performance note:</b> the instance returned is a singleton.
   */
  @SuppressWarnings("unchecked") // The natural-ordered empty set supports all types.
  public static <E> ImmutableSortedSet<E> of() {
    return (ImmutableSortedSet<E>) RegularImmutableSortedSet.NATURAL_EMPTY_SET;

    checkNotNull(supplier);
    return reference;
  }

  @Override
  public T orNull() {
    return reference;
  }

  @Override
  public Set<T> asSet() {
    return Collections.singleton(reference);
  }

  @Override
  public <V> Optional<V> transform(Function<? super T, V> function) {
    return new Present<>(
        checkNotNull(
            function.apply(reference),