}

      @Override
      public Entry<E> next() {
        if (!hasNext()) {
          throw new NoSuchElementException();
        }
        // requireNonNull is safe because current is only nulled out after iteration is complete.
        Entry<E> result = wrapEntry(requireNonNull(current));
        prevEntry = result;
        if (current.succ() == header) {
          current = null;
        } else {

    service.shutdown();
    Uninterruptibles.joinUninterruptibly(waiter, 10, TimeUnit.SECONDS);
    if (waiter.isAlive()) {
      waiter.interrupt();
      fail("awaitTermination failed to trigger after shutdown()");
    }
  }

  /** Wait for the given thread to reach the {@link State#TIMED_WAITING} thread state. */
  void awaitTimedWaiting(Thread thread) {
    while (true) {
      switch (thread.getState()) {

   *
   * <p>This is a "snapshot" based on the current topology of {@code graph}, rather than a live view
   * of the transitive closure of {@code graph}. In other words, the returned {@link Graph} will not
   * be updated after modifications to {@code graph}.
   *
   * @since 33.1.0 (present with return type {@code Graph} since 20.0)
   */
  // TODO(b/31438252): Consider potential optimizations for this algorithm.

              }
            }
          };
      executor.execute(errorTask);
      service.execute(barrierTask); // submit directly to the service
      // the barrier task runs after the error task so we know that the error has been observed by
      // SequentialExecutor by the time the barrier is satisfied
      barrier.await(1, TimeUnit.SECONDS);
      executor.execute(barrierTask);

      extends ImmutableEntry<K, V> implements ValueSetLink<K, V> {
    final int smearedValueHash;

    @CheckForNull ValueEntry<K, V> nextInValueBucket;
    /*
     * The *InValueSet and *InMultimap fields below are null after construction, but we almost
     * always call succeedsIn*() to initialize them immediately thereafter.
     *
     * The exception is the *InValueSet fields of multimapHeaderEntry, which are never set. (That

      extends ImmutableEntry<K, V> implements ValueSetLink<K, V> {
    final int smearedValueHash;

    @CheckForNull ValueEntry<K, V> nextInValueBucket;
    /*
     * The *InValueSet and *InMultimap fields below are null after construction, but we almost
     * always call succeedsIn*() to initialize them immediately thereafter.
     *
     * The exception is the *InValueSet fields of multimapHeaderEntry, which are never set. (That

   *
   * <p>This is a "snapshot" based on the current topology of {@code graph}, rather than a live view
   * of the transitive closure of {@code graph}. In other words, the returned {@link Graph} will not
   * be updated after modifications to {@code graph}.
   *
   * @since 33.1.0 (present with return type {@code Graph} since 20.0)
   */
  // TODO(b/31438252): Consider potential optimizations for this algorithm.

     *
     * - If the stack overflowed before set()/setValue() could even store the result in the output
     * Future, then a call setException() would likely also overflow.
     *
     * - If the stack overflowed after set()/setValue() stored its result, then a call to
     * setException() will be a no-op because the Future is already done.
     *
     * Both scenarios are bad: The output Future might never complete, or, if it does complete, it

 * together. Any creation method that would customarily respect insertion order (such as {@link
 * #copyOf(Multimap)}) instead preserves key-grouped order by inserting entries for an existing key
 * immediately after the last entry having that key.
 *
 * <p>See the Guava User Guide article on <a href=
 * "https://github.com/google/guava/wiki/ImmutableCollectionsExplained">immutable collections</a>.
 *
 * @author Jared Levy

   * from GC, as with {@link #awaitClear}. Because there are no guarantees for the order of GC
   * finalization processing, there may still be some unfinished work for the GC to do after this
   * method returns.
   *
   * <p>This method does not create any memory pressure as would be required to cause soft
   * references to be processed.
   *