* to test it.
       */
      return;
    }

    /*
     * Only under Windows (or hypothetically when running with some other non-POSIX, ACL-based
     * filesystem) does our prod code look up the username. Thus, this test doesn't necessarily test
     * anything interesting under most environments. Still, we can run it (except for Android, at

  // Use fewer steps in the ListIteratorTester in ListListIteratorTester because it's slow in prod
  // mode.
  static int listListIteratorTesterNumIterations() {
    // TODO(hhchan): It's 4 in java.  Figure out why even 3 is too slow in prod mode.
    return 2;
  }

  // Use fewer steps in the IteratorTester in CollectionIteratorTester because it's slow in prod
  // mode.
  static int collectionIteratorTesterNumIterations() {
    return 3;
  }

       * to test it.
       */
      return;
    }

    /*
     * Only under Windows (or hypothetically when running with some other non-POSIX, ACL-based
     * filesystem) does our prod code look up the username. Thus, this test doesn't necessarily test
     * anything interesting under most environments. Still, we can run it (except for Android, at

    executor.execute(task);
    assertEquals(1, numCalls.get());
  }

  /*
   * Under Android, MyError propagates up and fails the test?
   *
   * TODO(b/218700094): Does this matter to prod users, or is it just a feature of our testing
   * environment? If the latter, maybe write a custom Executor that avoids failing the test when it
   * sees an Error?
   */
  @AndroidIncompatible

   *
   * TODO(b/218700094): Ideally, get this to pass under Android. Failing that, convince ourselves
   * that the test isn't exposing a real problem with InterruptibleTask, one that could matter in
   * prod.
   */
  @AndroidIncompatible
  public void testInterruptIsSlow() throws Exception {
    final CountDownLatch isInterruptibleRegistered = new CountDownLatch(1);
    final SlowChannel slowChannel = new SlowChannel();

   *
   * TODO(b/218700094): Ideally, get this to pass under Android. Failing that, convince ourselves
   * that the test isn't exposing a real problem with InterruptibleTask, one that could matter in
   * prod.
   */
  @AndroidIncompatible
  public void testInterruptIsSlow() throws Exception {
    final CountDownLatch isInterruptibleRegistered = new CountDownLatch(1);
    final SlowChannel slowChannel = new SlowChannel();

    executor.execute(task);
    assertEquals(1, numCalls.get());
  }

  /*
   * Under Android, MyError propagates up and fails the test?
   *
   * TODO(b/218700094): Does this matter to prod users, or is it just a feature of our testing
   * environment? If the latter, maybe write a custom Executor that avoids failing the test when it
   * sees an Error?
   */
  @AndroidIncompatible

  private void setPredecessor(int entry, int pred) {
    long predMask = ~0L << 32;
    setLink(entry, (link(entry) & ~predMask) | ((long) (pred + 1) << 32));
  }

  private void setSucceeds(int pred, int succ) {
    if (pred == ENDPOINT) {
      firstEntry = succ;
    } else {
      setSuccessor(pred, succ);
    }

    if (succ == ENDPOINT) {
      lastEntry = pred;
    } else {

  }

  private void setPredecessor(int entry, int pred) {
    requirePredecessors()[entry] = pred + 1;
  }

  private void setSucceeds(int pred, int succ) {
    if (pred == ENDPOINT) {
      firstEntry = succ;
    } else {
      setSuccessor(pred, succ);
    }

    if (succ == ENDPOINT) {
      lastEntry = pred;
    } else {
      setPredecessor(succ, pred);
    }
  }

  @Override

    /** Constructor for the header node. */
    AvlNode() {
      this.elem = null;
      this.elemCount = 1;
    }

    // For discussion of pred() and succ(), see the comment on the pred and succ fields.

    private AvlNode<E> pred() {
      return requireNonNull(pred);
    }

    private AvlNode<E> succ() {
      return requireNonNull(succ);
    }