return (Collector) TO_OPTIONAL;
  }

  private static final Object NULL_PLACEHOLDER = new Object();

  private static final Collector<@Nullable Object, ?, @Nullable Object> ONLY_ELEMENT =
      Collector.<@Nullable Object, ToOptionalState<Object>, @Nullable Object>of(
          () -> new ToOptionalState<>(null),
          (state, o) -> state.add((o == null) ? NULL_PLACEHOLDER : o),
          ToOptionalState::combine,

        final String testKey = "domain.title";
        final int threadCount = 10;
        final Thread[] threads = new Thread[threadCount];
        final String[] results = new String[threadCount];

        for (int i = 0; i < threadCount; i++) {
            final int index = i;
            threads[i] = new Thread(() -> {
                results[index] = fessConfig.get(testKey);
            });
        }

     */
    @Test
    void testConcurrentWatch() throws Exception {
        // Create a thread-safe implementation
        SmbWatchHandle concurrentHandle = new SmbWatchHandle() {
            private final Object lock = new Object();
            private int watchCount = 0;

            @Override
            public List<FileNotifyInformation> watch() throws CIFSException {
                synchronized (lock) {

            try (Reader reader = IOUtils.getDecodingReader(new FileInputStream(suffixWordsFile), StandardCharsets.UTF_8)) {
                suffixWords = WordlistLoader.getWordSet(reader);
            } catch (final IOException e) {
                throw new IllegalArgumentException("Could not load " + suffixWordsFile.getAbsolutePath(), e);
            }
        } else {
            suffixWords = new CharArraySet(0, false);
        }
    }

        cipher.init(Cipher.ENCRYPT_MODE, new SecretKeySpec(keybytes, "AES"), new IvParameterSpec(ZERO_IV, 0, ZERO_IV.length));
        if (constant.length != cipher.getBlockSize()) {
            constant = expandNFold(constant, cipher.getBlockSize());
        }
        byte[] enc = constant;
        int klen = keybytes.length;
        byte[] dk = new byte[klen];
        for (int n = 0; n < klen;) {

        UserInfoCQ cq = new UserInfoCQ();
        if (queryLambda != null) {
            queryLambda.callback(cq);
        }
        FilterAggregationBuilder builder = regFilterA(name, cq.getQuery());
        if (opLambda != null) {
            opLambda.callback(builder);
        }
        if (aggsLambda != null) {
            UserInfoCA ca = new UserInfoCA();
            aggsLambda.callback(ca);

        BadWordCQ cq = new BadWordCQ();
        if (queryLambda != null) {
            queryLambda.callback(cq);
        }
        FilterAggregationBuilder builder = regFilterA(name, cq.getQuery());
        if (opLambda != null) {
            opLambda.callback(builder);
        }
        if (aggsLambda != null) {
            BadWordCA ca = new BadWordCA();
            aggsLambda.callback(ca);

        policeStoryOfJavaClassChase(new NonActionExtendsActionPolice());
        assertTrue(true);
    }

    @Test
    public void test_nonWebHasWebReference() throws Exception {
        policeStoryOfJavaClassChase(new NonWebHasWebReferencePolice());
        assertTrue(true);
    }

    @Test
    public void test_webPackageNinjaReferencePolice() throws Exception {
        policeStoryOfJavaClassChase(new WebPackageNinjaReferencePolice() {

    private final EventBus eventBus = new EventBus();

    @Subscribe
    public void handle(@Nullable Object unused) {}

    Subscriber toSubscriber() throws Exception {
      return Subscriber.create(eventBus, this, subscriberMethod());
    }

    SubscriberExceptionContext toContext() {
      return new SubscriberExceptionContext(eventBus, new Object(), this, subscriberMethod());
    }

        WebConfigCQ cq = new WebConfigCQ();
        if (queryLambda != null) {
            queryLambda.callback(cq);
        }
        FilterAggregationBuilder builder = regFilterA(name, cq.getQuery());
        if (opLambda != null) {
            opLambda.callback(builder);
        }
        if (aggsLambda != null) {
            WebConfigCA ca = new WebConfigCA();
            aggsLambda.callback(ca);