TearDownStack result = new TearDownStack();
    tearDownStack.addTearDown(
        new TearDown() {

          @Override
          public void tearDown() throws Exception {
            synchronized (result.lock) {
              assertEquals(
                  "The test should have cleared the stack (say, by virtue of running runTearDown)",
                  0,
                  result.stack.size());

        final int[] callCount = { 0 };

        SearchLogHelper mockSearchLogHelper = new SearchLogHelper() {
            @Override
            public void storeSearchLog() {
                synchronized (lock) {
                    callCount[0]++;
                    if (callCount[0] % 2 == 0) {
                        throw new RuntimeException("Even call error");
                    }

    address: Address,
    connectionUser: ConnectionUser,
    routes: List<Route>?,
    requireMultiplexed: Boolean,
  ): RealConnection? {
    for (connection in connections) {
      // In the first synchronized block, acquire the connection if it can satisfy this call.
      val acquired =
        connection.withLock {
          when {
            requireMultiplexed && !connection.isMultiplexed -> false

    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:

        }
        buffer.setLength(buffer.length() - ", ".length());
        return new String(buffer);
    }

    /**
     * Initializes the class.
     */
    protected static synchronized void initialize() {
        if (!initialized) {
            DisposableUtil.add(() -> {
                ResourceBundle.clearCache();
                initialized = false;
            });

                            boolean contains = pool.contains(null); // Should handle gracefully
                            successCount.incrementAndGet();
                        } catch (Exception e) {
                            synchronized (exceptions) {
                                exceptions.add(e);
                            }
                        }
                    }
                    long threadEnd = System.nanoTime();

  if (position.index == length) {
    // STANDARD_DATE_FORMAT must match exactly; all text must be consumed, e.g. no ignored
    // non-standard trailing "+01:00". Those cases are covered below.
    return result
  }
  synchronized(BROWSER_COMPATIBLE_DATE_FORMAT_STRINGS) {
    for (i in 0 until BROWSER_COMPATIBLE_DATE_FORMAT_STRINGS.size) {
      var format: DateFormat? = BROWSER_COMPATIBLE_DATE_FORMATS[i]
      if (format == null) {
        format =

            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);

            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: