/**
   * If the graph is undirected, each unordered [node, otherNode] pair (except self-loops) will be
   * visited twice if there is an edge connecting them. To avoid returning duplicate {@link
   * EndpointPair}s, we keep track of the nodes that we have visited. When processing endpoint
   * pairs, we skip if the "other node" is in the visited set, as shown below:
   *
   * <pre>
   * Nodes = {N1, N2, N3, N4}
   *    N2           __

  /**
   * Returns the number of edges in this graph; used to calculate the size of {@link Graph#edges()}.
   * This implementation requires O(|N|) time. Classes extending this one may manually keep track of
   * the number of edges as the graph is updated, and override this method for better performance.
   */
  protected long edgeCount() {
    long degreeSum = 0L;
    for (N node : nodes()) {

import java.util.concurrent.atomic.AtomicInteger;
import junit.framework.TestCase;

/**
 * Basher test for {@link ConcurrentHashMultiset}: start a bunch of threads, have each of them do
 * operations at random. Each thread keeps track of the per-key deltas that it's directly
 * responsible for; after all threads have completed, we sum the per-key deltas and compare to the
 * existing multiset values.
 *
 * @author mike nonemacher
 */

      ReferenceQueue<Object> queue,
      PhantomReference<Object> frqReference) {
    this.queue = queue;

    this.finalizableReferenceClassReference = new WeakReference<>(finalizableReferenceClass);

    // Keep track of the FRQ that started us so we know when to stop.
    this.frqReference = frqReference;
  }

  /** Loops continuously, pulling references off the queue and cleaning them up. */

      ReferenceQueue<Object> queue,
      PhantomReference<Object> frqReference) {
    this.queue = queue;

    this.finalizableReferenceClassReference = new WeakReference<>(finalizableReferenceClass);

    // Keep track of the FRQ that started us so we know when to stop.
    this.frqReference = frqReference;
  }

  /** Loops continuously, pulling references off the queue and cleaning them up. */

  @VisibleForTesting @CheckForNull transient @Nullable Object[] elements;

  /**
   * Keeps track of metadata like the number of hash table bits and modifications of this data
   * structure (to make it possible to throw ConcurrentModificationException in the iterator). Note
   * that we choose not to make this volatile, so we do less of a "best effort" to track such
   * errors, for better performance.
   */
  private transient int metadata;

  @VisibleForTesting @CheckForNull transient @Nullable Object[] values;

  /**
   * Keeps track of metadata like the number of hash table bits and modifications of this data
   * structure (to make it possible to throw ConcurrentModificationException in the iterator). Note
   * that we choose not to make this volatile, so we do less of a "best effort" to track such
   * errors, for better performance.
   *

   * a request itself.
   *
   * @since 31.0
   */
  public static final String X_DEVICE_REQUESTED_WITH = "X-Device-Requested-With";
  /** The HTTP {@code X-Do-Not-Track} header field name. */
  public static final String X_DO_NOT_TRACK = "X-Do-Not-Track";
  /** The HTTP {@code X-Forwarded-For} header field name (superseded by {@code Forwarded}). */
  public static final String X_FORWARDED_FOR = "X-Forwarded-For";

  @VisibleForTesting @CheckForNull transient @Nullable Object[] values;

  /**
   * Keeps track of metadata like the number of hash table bits and modifications of this data
   * structure (to make it possible to throw ConcurrentModificationException in the iterator). Note
   * that we choose not to make this volatile, so we do less of a "best effort" to track such
   * errors, for better performance.
   *

      int n, @Nullable Entry<K, V>[] entryArray, boolean throwIfDuplicateKeys) {
    Map<K, V> delegateMap = Maps.newHashMapWithExpectedSize(n);
    // If duplicates are allowed, this map will track the last value for each duplicated key.
    // A second pass will retain only the first entry for that key, but with this last value. The
    // value will then be replaced by null, signaling that later entries with the same key should