return construct(array);
  }

  /**
   * Returns an immutable list containing the given elements, in order. If {@code elements} is a
   * {@link Collection}, this method behaves exactly as {@link #copyOf(Collection)}; otherwise, it
   * behaves exactly as {@code copyOf(elements.iterator()}.
   *
   * @throws NullPointerException if {@code elements} contains a null element
   */

   * and leaves, calling signalNextWaiter. With traditional locks and conditions, all the conditions
   * need to be signalled because it is not known which if any of them have waiters (and hasWaiters
   * can't be used reliably because of a check-then-act race). With our Monitor guards, we only
   * signal the first active guard that is satisfied. But the corresponding thread may have already

   * appear in either that iterator or any other iterator created from the same source iterable.
   * That is, this method behaves exactly as {@code Iterables.cycle(Lists.newArrayList(elements))}.
   * The iterator's {@code hasNext} method returns {@code true} until all of the original elements
   * have been removed.
   *
   * <p><b>Warning:</b> Typical uses of the resulting iterator may produce an infinite loop. You

   * we're guaranteed to have properly initialized the subclass.
   */
  final void init() {
    /*
     * requireNonNull is safe because this is called from the constructor after `futures` is set but
     * before releaseResources could be called (because we have not yet set up any of the listeners

    // (b) Waiting for the single guard to become satisfied.
    // (c) Occupying the monitor and awaiting the tearDownLatch.
    //
    // Except for (c), every thread should occupy the monitor very briefly, and every thread leaves
    // the monitor with the guard satisfied. Therefore as soon as tearDownLatch is triggered, we
    // should be able to enter the monitor, and then we set the guard to satisfied for the benefit

  @CheckForNull
  public E peekLast() {
    return isEmpty() ? null : elementData(getMaxElementIndex());
  }

  /**
   * Removes the element at position {@code index}.
   *
   * <p>Normally this method leaves the elements at up to {@code index - 1}, inclusive, untouched.
   * Under these circumstances, it returns {@code null}.
   *
   * <p>Occasionally, in order to maintain the heap invariant, it must swap a later element of the

   * tasks. Second, the returned list will always be empty, as any submitted task is considered to
   * have started execution. This applies also to tasks given to {@code invokeAll} or {@code
   * invokeAny} which are pending serial execution, even the subset of the tasks that have not yet
   * started execution. It is unclear from the {@code ExecutorService} specification if these should

  /**
   * Returns an encoding that behaves equivalently to this encoding, but omits any padding
   * characters as specified by <a href="http://tools.ietf.org/html/rfc4648#section-3.2">RFC 4648
   * section 3.2</a>, Padding of Encoded Data.
   */
  public abstract BaseEncoding omitPadding();

  /**
   * Returns an encoding that behaves equivalently to this encoding, but uses an alternate character

   *
   * <p><b>Comparison to {@code java.util.Optional}:</b> this class leaves the specific choice of
   * hash code unspecified, unlike the Java 8+ equivalent.
   */
  @Override
  public abstract int hashCode();

  /**
   * Returns a string representation for this instance.
   *
   * <p><b>Comparison to {@code java.util.Optional}:</b> this class leaves the specific string

 * including those in many JDK classes.
 *
 * <p>{@code Object.hashCode} implementations tend to be very fast, but have weak collision
 * prevention and <i>no</i> expectation of bit dispersion. This leaves them perfectly suitable for
 * use in hash tables, because extra collisions cause only a slight performance hit, while poor bit