}
    };
  }

  @Override
  public Iterator<EndpointPair<N>> incidentEdgeIterator(N thisNode) {
    checkNotNull(thisNode);

    Iterator<EndpointPair<N>> resultWithDoubleSelfLoop;
    if (orderedNodeConnections == null) {
      resultWithDoubleSelfLoop =
          Iterators.concat(
              Iterators.transform(
                  predecessors().iterator(),

    }
  }

  /**
   * Verifies that an Iterator is unmodifiable.
   *
   * <p>This test only works with iterators that iterate over a finite set.
   */
  public static void assertIteratorIsUnmodifiable(Iterator<?> iterator) {
    while (iterator.hasNext()) {
      iterator.next();
      try {
        iterator.remove();
        fail("Remove on unmodifiable iterator succeeded");

        @Override
        public @Nullable Object execute(Iterator<?> iterator) {
          iterator.remove();
          return null;
        }
      };

  private static final IteratorOperation NEXT_METHOD =
      new IteratorOperation() {
        @Override
        public @Nullable Object execute(Iterator<?> iterator) {
          return iterator.next();
        }
      };

    final Iterator<Entry<K, Collection<V>>> keyIterator;
    @CheckForNull K key;
    @CheckForNull Collection<V> collection;
    Iterator<V> valueIterator;

    Itr() {
      keyIterator = map.entrySet().iterator();
      key = null;
      collection = null;
      valueIterator = Iterators.emptyModifiableIterator();
    }

    // current[i]_ is the actual traversing iterator.
    const typename ParamGenerator<T1>::iterator begin1_;
    const typename ParamGenerator<T1>::iterator end1_;
    typename ParamGenerator<T1>::iterator current1_;
    const typename ParamGenerator<T2>::iterator begin2_;
    const typename ParamGenerator<T2>::iterator end2_;
    typename ParamGenerator<T2>::iterator current2_;

    }
  }

  /**
   * Verifies that an Iterator is unmodifiable.
   *
   * <p>This test only works with iterators that iterate over a finite set.
   */
  public static void assertIteratorIsUnmodifiable(Iterator<?> iterator) {
    while (iterator.hasNext()) {
      iterator.next();
      try {
        iterator.remove();
        fail("Remove on unmodifiable iterator succeeded");

    // current[i]_ is the actual traversing iterator.
    const typename ParamGenerator<T1>::iterator begin1_;
    const typename ParamGenerator<T1>::iterator end1_;
    typename ParamGenerator<T1>::iterator current1_;
    const typename ParamGenerator<T2>::iterator begin2_;
    const typename ParamGenerator<T2>::iterator end2_;
    typename ParamGenerator<T2>::iterator current2_;

    }

    @Override
    public void clear() {
        delegate.clear();
        listener.onClear();
    }

    @Override
    public Iterator<E> iterator() {
        reportAggregatingAccess();
        return Iterators.transform(delegate().iterator(), factory::apply);
    }

    @Override
    public int size() {
        reportAggregatingAccess();
        return delegate.size();
    }

    final Iterator<Entry<K, Collection<V>>> keyIterator;
    @CheckForNull K key;
    @CheckForNull Collection<V> collection;
    Iterator<V> valueIterator;

    Itr() {
      keyIterator = map.entrySet().iterator();
      key = null;
      collection = null;
      valueIterator = Iterators.emptyModifiableIterator();
    }

  final transient Collection<E> delegate;

  ForwardingImmutableCollection(Collection<E> delegate) {
    this.delegate = delegate;
  }

  @Override
  public UnmodifiableIterator<E> iterator() {
    return Iterators.unmodifiableIterator(delegate.iterator());
  }

  @Override
  public boolean contains(@Nullable Object object) {
    return object != null && delegate.contains(object);
  }

  @Override