}

  final Set<K> unmodifiableKeySet() {
    return new AbstractSet<K>() {
      @Override
      public UnmodifiableIterator<K> iterator() {
        Iterator<Entry<K, V>> entryIterator = backingMap.entrySet().iterator();

        return new UnmodifiableIterator<K>() {
          @Override
          public boolean hasNext() {
            return entryIterator.hasNext();
          }

  }

  /**
   * Returns a sequential {@link Stream} of the remaining contents of {@code iterator}. Do not use
   * {@code iterator} directly after passing it to this method.
   */
  public static <T extends @Nullable Object> Stream<T> stream(Iterator<T> iterator) {
    return StreamSupport.stream(Spliterators.spliteratorUnknownSize(iterator, 0), false);
  }

  /**

    Set<Entry<Integer, String>> entries = map.entrySet();
    Iterator<Entry<Integer, String>> iterator = entries.iterator();
    Entry<Integer, String> entry = iterator.next();
    entry.setValue("two"); // changes the iterator's current entry value
    assertEquals("two", map.get(1));
    assertEquals(Integer.valueOf(1), map.inverse().get("two"));
    iterator.remove(); // removes the updated entry
    assertTrue(map.isEmpty());
  }

            return parent.isEmpty();
        }

        public boolean contains(final Object o) {
            return parent.contains(o);
        }

        public Iterator<E> iterator() {
            return parent.iterator();
        }

        public Object[] toArray() {
            return parent.toArray();
        }

        public <T> T[] toArray(final T[] a) {

        return new AbstractSet<EndpointPair<N>>() {
          @Override
          public Iterator<EndpointPair<N>> iterator() {
            return Iterators.transform(
                AbstractNetwork.this.edges().iterator(), edge -> incidentNodes(edge));
          }

          @Override
          public int size() {
            return AbstractNetwork.this.edges().size();

import org.jspecify.annotations.Nullable;

/**
 * This class provides a skeletal implementation of the {@code Iterator} interface for sequences
 * whose next element can always be derived from the previous element. Null elements are not
 * supported, nor is the {@link #remove()} method.
 *
 * <p>Example:
 *
 * {@snippet :
 * Iterator<Integer> powersOfTwo =
 *     new AbstractSequentialIterator<Integer>(1) {

    this.targetNode = checkNotNull(targetNode);
  }

  @Override
  public UnmodifiableIterator<E> iterator() {
    E connectingEdge = getConnectingEdge();
    return (connectingEdge == null)
        ? ImmutableSet.<E>of().iterator()
        : Iterators.singletonIterator(connectingEdge);
  }

  @Override
  public int size() {
    return getConnectingEdge() == null ? 0 : 1;
  }

        StringBuilder projectNames = new StringBuilder();
        Iterator<MavenProject> iterator = projects.iterator();
        while (iterator.hasNext()) {
            MavenProject project = iterator.next();
            projectNames.append(project.getGroupId()).append(":").append(project.getArtifactId());
            if (iterator.hasNext()) {
                projectNames.append(", ");
            }
        }

        List<String> stubSiteCycle =
                Arrays.asList(PRE_SITE.getPhase(), SITE.getPhase(), POST_SITE.getPhase(), SITE_DEPLOY.getPhase());

        Iterator<List<String>> lcs =
                Arrays.asList(stubDefaultCycle, stubCleanCycle, stubSiteCycle).iterator();

        Map<String, Lifecycle> lifeCycles = new HashMap<>();
        for (String s : DefaultLifecycles.STANDARD_LIFECYCLES) {

    }

    @Override
    public boolean include(Artifact artifact) {
        String id = artifact.getGroupId() + ":" + artifact.getArtifactId();

        boolean matched = false;
        for (Iterator<String> i = patterns.iterator(); i.hasNext() & !matched; ) {
            // TODO what about wildcards? Just specifying groups? versions?
            if (id.equals(i.next())) {
                matched = true;
            }
        }