}

    @Test
    public void test_crawlerList_synchronization() {
        // Test that the crawler list is synchronized
        List<org.codelibs.fess.crawler.Crawler> crawlerList = webFsIndexHelper.crawlerList;
        assertTrue(crawlerList.getClass().getName().contains("Synchronized"));
    }

    @Test
    public void test_defaultValues() {

    @Override
    public DefaultSettingsBuildingRequest setSystemProperties(Properties systemProperties) {
        if (systemProperties != null) {
            this.systemProperties = new Properties();
            synchronized (systemProperties) { // avoid concurrent modification if someone else sets/removes an unrelated
                // system property
                this.systemProperties.putAll(systemProperties);
            }

  static class Key {
    private final int value;
    private WeakReference<String> toString;

    Key(int value) {
      this.value = value;
    }

    @Override
    public synchronized String toString() {
      String s;
      if (toString != null) {
        s = toString.get();
        if (s != null) {
          return s;
        }
      }
      s = Integer.toString(value);

    }
    enumConstantCache.put(enumClass, result);
    return result;
  }

  static <T extends Enum<T>> Map<String, WeakReference<? extends Enum<?>>> getEnumConstants(
      Class<T> enumClass) {
    synchronized (enumConstantCache) {
      Map<String, WeakReference<? extends Enum<?>>> constants = enumConstantCache.get(enumClass);
      if (constants == null) {
        constants = populateCache(enumClass);
      }

   *
   * @param bimap the bimap to be wrapped in a synchronized view
   * @return a synchronized view of the specified bimap
   */
  @J2ktIncompatible // Synchronized
  public static <K extends @Nullable Object, V extends @Nullable Object>
      BiMap<K, V> synchronizedBiMap(BiMap<K, V> bimap) {
    return Synchronized.biMap(bimap, null);
  }

  /**

     */
    private final int priority;

    /**
     * Parses the phase identifier.
     *
     * @param phase the phase identifier.
     * @return the {@link PhaseId}.
     */
    public static synchronized PhaseId of(String phase) {
        return INSTANCES.computeIfAbsent(phase, PhaseId::new);
    }

    /**
     * Constructor.
     *
     * @param phase the phase identifier string.
     */

/**
 * @deprecated use {@code org.apache.maven.api.services.ModelBuilder} instead
 */
@Deprecated(since = "4.0.0")
class Graph {

    final Map<String, Set<String>> graph = new LinkedHashMap<>();

    synchronized void addEdge(String from, String to) throws CycleDetectedException {
        if (graph.computeIfAbsent(from, l -> new HashSet<>()).add(to)) {

  private TearDownStack buildTearDownStack() {
    TearDownStack result = new TearDownStack();
    tearDownStack.addTearDown(
        () -> {
          synchronized (result.lock) {
            assertEquals(
                "The test should have cleared the stack (say, by virtue of running runTearDown)",
                0,
                result.stack.size());
          }

    /**
     * Returns a {@link Logger}.
     *
     * @param clazz
     *            Class to be used as the logger category. Must not be {@literal null}.
     * @return {@link Logger}
     */
    public static synchronized Logger getLogger(final Class<?> clazz) {
        assertArgumentNotNull("clazz", clazz);

        if (!initialized) {
            initialize();
        }
        Logger logger = loggers.get(clazz);

    abstract val fileSystemOperations: FileSystemOperations

    private
    var hasCleaned = false

    val logger = Logging.getLogger(CachesCleaner::class.java)

    fun cleanUpCaches() {
        synchronized(this) {
            if (hasCleaned) {
                return
            }
            logger.lifecycle("Cleaning up caches...")
            val homeDir = parameters.homeDir.get()