Comparator<?> comparator = set.comparator();
      if (Ordering.<C>natural().equals(comparator) || comparator == null) {
        return closed(set.first(), set.last());
      }
    }
    Iterator<C> valueIterator = values.iterator();
    C min = checkNotNull(valueIterator.next());
    C max = min;
    while (valueIterator.hasNext()) {
      C value = checkNotNull(valueIterator.next());

        .createTestSuite();
  }

  // Not specifying KNOWN_ORDER for PriorityQueue and PriorityBlockingQueue
  // even though they do have it, because our tests interpret KNOWN_ORDER to
  // also mean that the iterator returns the head element first, which those
  // don't.

  public Test testsForPriorityBlockingQueue() {
    return QueueTestSuiteBuilder.using(
            new TestStringQueueGenerator() {
              @Override

        return value;
      }
    };
  }

  private static <K extends @Nullable Object, V extends @Nullable Object> Entry<K, V> control(
      K key, V value) {
    return singletonMap(key, value).entrySet().iterator().next();
  }

  public void testToString() {
    assertEquals("foo=1", entry("foo", 1).toString());
  }

  public void testToStringNull() {
    assertEquals("null=1", entry(NK, 1).toString());

import java.util.AbstractSet;
import java.util.Set;
import org.jspecify.annotations.Nullable;

/**
 * Abstract base class for an incident edges set that allows different implementations of {@link
 * AbstractSet#iterator()}.
 */
abstract class IncidentEdgeSet<N> extends AbstractSet<EndpointPair<N>> {
  final N node;
  final ArchetypeGraph<N> graph;
  final EdgeType edgeType;

  enum EdgeType {

import java.util.AbstractSet;
import java.util.Set;
import org.jspecify.annotations.Nullable;

/**
 * Abstract base class for an incident edges set that allows different implementations of {@link
 * AbstractSet#iterator()}.
 */
abstract class IncidentEdgeSet<N> extends AbstractSet<EndpointPair<N>> {
  final N node;
  final ArchetypeGraph<N> graph;
  final EdgeType edgeType;

  enum EdgeType {

   * <i>only</i> if the caller knows that the collection does not contain any null elements.
   *
   * <p>This method returns the elements in the order they are returned by the collection's
   * iterator.
   *
   * <p>TODO(kevinb): support concurrently modified collections?
   *
   * @param c the collection for which to return an array of elements
   * @param array the array in which to place the collection elements

    return false;
  }

  @GwtIncompatible // not used by GWT emulation
  @Override
  int indexOf(@Nullable Object target) {
    return -1;
  }

  @Override
  public UnmodifiableIterator<C> iterator() {
    return emptyIterator();
  }

  @GwtIncompatible // NavigableSet
  @Override
  public UnmodifiableIterator<C> descendingIterator() {
    return emptyIterator();
  }

  @Override

  // (In the backport, we don't need this suppression, but we keep it to minimize diffs.)
  @SuppressWarnings("unchecked")
  @Override
  public UnmodifiableIterator<E> iterator() {
    return (UnmodifiableIterator<E>) Iterators.forArray(elements);
  }

  @Override
  public Spliterator<E> spliterator() {
    return Spliterators.spliterator(elements, SPLITERATOR_CHARACTERISTICS);
  }

    for (Node t : iterable) {
      builder.append(t.value);
    }
    StringBuilder forEachBuilder = new StringBuilder();
    iterable.forEach(t -> forEachBuilder.append(t.value));
    assertTrue(
        "Iterator content was " + builder + " but forEach content was " + forEachBuilder,
        builder.toString().contentEquals(forEachBuilder));
    return builder.toString();
  }

  public void testPreOrder() {

  // Refined Collection Methods

  /**
   * {@inheritDoc}
   *
   * <p>Elements that occur multiple times in the multiset will appear multiple times in this
   * iterator, though not necessarily sequentially.
   */
  @Override
  Iterator<E> iterator();

  /**
   * Determines whether this multiset contains the specified element.
   *