}
    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);
      }

            if (name.startsWith(concurrentPackage)
                // Use other classloader for ListenableFuture, so that the objects can interact
                && !ListenableFuture.class.getName().equals(name)) {
              synchronized (loadedClasses) {
                Class<?> toReturn = loadedClasses.get(name);
                if (toReturn == null) {
                  toReturn = super.findClass(name);
                  loadedClasses.put(name, toReturn);

    assertTrue(Thread.holdsLock(mutex));
    return super.isEmpty();
  }

  /*
   * We don't assert that the lock is held during calls to iterator(), stream(), and spliterator:
   * `Synchronized` doesn't guarantee that it will hold the mutex for those calls because callers
   * are responsible for taking the mutex themselves:

            if (name.startsWith(concurrentPackage)
                // Use other classloader for ListenableFuture, so that the objects can interact
                && !ListenableFuture.class.getName().equals(name)) {
              synchronized (loadedClasses) {
                Class<?> toReturn = loadedClasses.get(name);
                if (toReturn == null) {
                  toReturn = super.findClass(name);
                  loadedClasses.put(name, toReturn);

 * strategies.
 *
 * <ul>
 *   <li>SafeAtomicHelper: uses Atomic FieldsUpdaters to implement synchronization
 *   <li>SynchronizedHelper: uses {@code synchronized} blocks for synchronization
 * </ul>
 *
 * To force selection of our fallback strategies we load {@link AggregateFutureState} (and all of

                this.uhe = uhe;
            } catch (final Exception ex) {
                this.uhe = new UnknownHostException(ex.getMessage());
            } finally {
                synchronized (sem) {
                    sem.count--;
                    sem.notify();
                }
            }
        }
    }

 * strategies.
 *
 * <ul>
 *   <li>SafeAtomicHelper: uses Atomic FieldsUpdaters to implement synchronization
 *   <li>SynchronizedHelper: uses {@code synchronized} blocks for synchronization
 * </ul>
 *
 * To force selection of our fallback strategies we load {@link AggregateFutureState} (and all of

  }

  private static class TestApplication extends Application {
    private final List<Thread> hooks = new ArrayList<>();

    @Override
    synchronized void addShutdownHook(Thread hook) {
      hooks.add(hook);
    }

    synchronized void shutdown() throws InterruptedException {
      for (Thread hook : hooks) {
        hook.start();
      }
      for (Thread hook : hooks) {
        hook.join();

   * @return a synchronized view of the specified navigable set.
   * @since 13.0
   */
  @GwtIncompatible // NavigableSet
  @J2ktIncompatible // Synchronized
  public static <E extends @Nullable Object> NavigableSet<E> synchronizedNavigableSet(
      NavigableSet<E> navigableSet) {
    return Synchronized.navigableSet(navigableSet);
  }

    private static class IOExceptionOccurProperties extends Properties {

        /**
         *
         */
        private static final long serialVersionUID = 1L;

        @Override
        public synchronized void load(final InputStream inStream) throws IOException {
            throw new IOException("load");
        }

    }

    /**
     * {@link org.codelibs.core.io.PropertiesUtil#load(Properties, String)}