firstException = expected;
    // Second time should also fail, with a cached causal chain.
    expected = assertThrows(PotentialDeadlockException.class, () -> lockA.lock());
    checkMessage(expected, "LockB -> LockA", "LockA -> LockB");
    // The causal chain should be cached.
    assertSame(firstException.getCause(), expected.getCause());
    // lockA should work after lockB is released.

    // the slower pointer, then there's a loop.
    Throwable slowPointer = throwable;
    boolean advanceSlowPointer = false;

    Throwable cause;
    while ((cause = throwable.getCause()) != null) {
      throwable = cause;
      causes.add(throwable);

      if (throwable == slowPointer) {

    // the slower pointer, then there's a loop.
    Throwable slowPointer = throwable;
    boolean advanceSlowPointer = false;

    Throwable cause;
    while ((cause = throwable.getCause()) != null) {
      throwable = cause;
      causes.add(throwable);

      if (throwable == slowPointer) {

    firstException = expected;
    // Second time should also fail, with a cached causal chain.
    expected = assertThrows(PotentialDeadlockException.class, () -> lockA.lock());
    checkMessage(expected, "LockB -> LockA", "LockA -> LockB");
    // The causal chain should be cached.
    assertSame(firstException.getCause(), expected.getCause());
    // lockA should work after lockB is released.

   * of {@code ExampleStackTrace} instances to illustrate the cycle, e.g.
   *
   * <pre>
   * com....PotentialDeadlockException: Potential Deadlock from LockC -&gt; ReadWriteA
   *   at ...
   *   at ...
   * Caused by: com...ExampleStackTrace: LockB -&gt; LockC
   *   at ...
   *   at ...
   * Caused by: com...ExampleStackTrace: ReadWriteA -&gt; LockB

      boolean completedWithFailure = setException(throwable);
      if (!completedWithFailure) {
        // Go up the causal chain to see if we've already seen this cause; if we have, even if
        // it's wrapped by a different exception, don't log it.
        boolean firstTimeSeeingThisException = addCausalChain(getOrInitSeenExceptions(), throwable);

    CountDownLatch latch = new CountDownLatch(1);
    // Setting a security manager causes the common ForkJoinPool to use InnocuousThreads with no
    // permissions.
    // submit()/join() causes this thread to execute the task instead, so we use a CountDownLatch as
    // a barrier to synchronize.

    tests, either. This causes it to fail to find AtomicLongMapTest.

    Our workaround is to tell GWT that util.concurrent and all other packages
    have prod supersource, even if they have none. GWT is happy to ignore us
    when we specify a nonexistent path.

    (I hope that this workaround does not cause its own problems in the future.)
-->
<super-source path="super"/>

    tests, either. This causes it to fail to find AtomicLongMapTest.

    Our workaround is to tell GWT that util.concurrent and all other packages
    have prod supersource, even if they have none. GWT is happy to ignore us
    when we specify a nonexistent path.

    (I hope that this workaround does not cause its own problems in the future.)
-->
<super-source path="super"/>

    tests, either. This causes it to fail to find AtomicLongMapTest.

    Our workaround is to tell GWT that util.concurrent and all other packages
    have prod supersource, even if they have none. GWT is happy to ignore us
    when we specify a nonexistent path.

    (I hope that this workaround does not cause its own problems in the future.)
-->
<super-source path="super"/>