return;
    }

    Set<Entry<K, V>> entrySet = map.entrySet();
    Iterator<Entry<K, V>> iterator = entrySet.iterator();
    if (supportsIteratorRemove) {
      int initialSize = map.size();
      Entry<K, V> entry = iterator.next();
      Entry<K, V> entryCopy = mapEntry(entry.getKey(), entry.getValue());

      iterator.remove();
      assertEquals(initialSize - 1, map.size());

  public void testPutAbsentConcurrentWithEntrySetIteration() {
    assertThrows(
        ConcurrentModificationException.class,
        () -> {
          Iterator<Entry<K, V>> iterator = getMap().entrySet().iterator();
          put(e3());
          iterator.next();
        });
  }

  @MapFeature.Require({FAILS_FAST_ON_CONCURRENT_MODIFICATION, SUPPORTS_PUT})
  @CollectionSize.Require(absent = ZERO)

  }

  @CollectionFeature.Require(absent = SUPPORTS_REMOVE)
  @CollectionSize.Require(absent = ZERO)
  public void testIteratorRemove_unsupported() {
    Iterator<E> iterator = collection.iterator();
    iterator.next();
    assertThrows(UnsupportedOperationException.class, iterator::remove);
    expectUnchanged();
    assertTrue(collection.contains(e0()));
  }

  @CollectionFeature.Require(SUPPORTS_REMOVE)

    Iterator<Entry<K, V>> iterator = multimap().entries().iterator();
    assertEquals(mapEntry(k0(), v0()), iterator.next());
    iterator.remove();
    assertTrue(multimap().isEmpty());
  }

  @CollectionSize.Require(absent = ZERO)
  @MapFeature.Require(SUPPORTS_REMOVE)
  public void testEntriesRemainValidAfterRemove() {
    Iterator<Entry<K, V>> iterator = multimap().entries().iterator();

  public void testCopyOf_iterator_empty() {
    Iterator<String> iterator = emptyIterator();
    Set<String> set = copyOf(iterator);
    assertEquals(Collections.<String>emptySet(), set);
    assertSame(this.<String>of(), set);
  }

  public void testCopyOf_iterator_oneElement() {
    Iterator<String> iterator = singletonIterator("a");
    Set<String> set = copyOf(iterator);
    assertEquals(singleton("a"), set);
  }

    } else if (isEmpty()) {
      return true;
    }

    if (SortedIterables.hasSameComparator(comparator, that)) {
      Iterator<?> otherIterator = that.iterator();
      try {
        Iterator<E> iterator = iterator();
        while (iterator.hasNext()) {
          Object element = iterator.next();
          Object otherElement = otherIterator.next();

      return Collections.unmodifiableSet(adjacentNodeValues.keySet());
    } else {
      return new AbstractSet<N>() {
        @Override
        public UnmodifiableIterator<N> iterator() {
          Iterator<NodeConnection<N>> nodeConnections = orderedNodeConnections.iterator();
          Set<N> seenNodes = new HashSet<>();
          return new AbstractIterator<N>() {
            @Override
            protected @Nullable N computeNext() {

  /**
   * A sensible definition of {@link #firstEntry()} in terms of {@code entrySet().iterator()}.
   *
   * <p>If you override {@link #entrySet()}, you may wish to override {@link #firstEntry()} to
   * forward to this implementation.
   */
  protected @Nullable Entry<E> standardFirstEntry() {
    Iterator<Entry<E>> entryIterator = entrySet().iterator();
    if (!entryIterator.hasNext()) {
      return null;
    }

    return appendTo(appendable, parts.iterator());
  }

  /**
   * Appends the string representation of each of {@code parts}, using the previously configured
   * separator between each, to {@code appendable}.
   *
   * @since 11.0
   */
  @CanIgnoreReturnValue
  public <A extends Appendable> A appendTo(A appendable, Iterator<?> parts) throws IOException {
    checkNotNull(appendable);

    assertEquals("", j.join(ImmutableMultimap.of().entries().iterator()));
    assertEquals(":", j.join(ImmutableMultimap.of("", "").entries()));
    assertEquals(":", j.join(ImmutableMultimap.of("", "").entries().iterator()));
    assertEquals("1:a;1:b", j.join(ImmutableMultimap.of("1", "a", "1", "b").entries()));
    assertEquals("1:a;1:b", j.join(ImmutableMultimap.of("1", "a", "1", "b").entries().iterator()));