static final String EDGE_ALREADY_EXISTS = "Edge %s already exists in the graph.";
  static final String ENDPOINTS_MISMATCH =
      "Mismatch: endpoints' ordering is not compatible with directionality of the graph";

  /** Singleton edge value for {@link Graph} implementations backed by {@link ValueGraph}s. */
  enum Presence {
    EDGE_EXISTS
  }

   * @since 6.0 (source-compatible since 2.0)
   */
  public static <E> ImmutableMultiset<E> of(E element) {
    return copyFromElements(element);
  }

  /**
   * Returns an immutable multiset containing the given elements, in order.
   *
   * @throws NullPointerException if any element is null
   * @since 6.0 (source-compatible since 2.0)
   */

  // TODO(chrisn): promote AppendOnlyCollection for use here.
  private final List<PerListenerQueue<L>> listeners =
      Collections.synchronizedList(new ArrayList<PerListenerQueue<L>>());

  /** Method reference-compatible listener event. */
  interface Event<L> {
    /** Call a method on the listener. */
    void call(L listener);
  }

  /**

      return false;
    }
    return hasEdgeConnecting(endpoints.nodeU(), endpoints.nodeV());
  }

  /**
   * Throws an IllegalArgumentException if the ordering of {@code endpoints} is not compatible with
   * the directionality of this graph.
   */
  protected final void validateEndpoints(EndpointPair<?> endpoints) {
    checkNotNull(endpoints);

 */

package com.google.common.util.concurrent.internal;


/**
 * Static utilities for {@link InternalFutureFailureAccess}. Most users will never need to use this
 * class.
 *
 * <p>This class is GWT-compatible.
 *
 * @since {@code com.google.guava:failureaccess:1.0}, which was added as a dependency of Guava in
 *     Guava 27.0
 */
public final class InternalFutures {
  /**

 * serialization tests require more setup. This no-op behavior allows test authors to intersperse
 * {@code SerializableTester} calls with other, GWT-compatible tests.
 *
 * @author Mike Bostock
 * @since 10.0
 */
@GwtCompatible // but no-op!
@ElementTypesAreNonnullByDefault
public final class SerializableTester {
  private SerializableTester() {}

  /**

  public static <K extends Comparable, V extends @Nullable Object>
      Iterable<Entry<K, V>> orderEntriesByKey(List<Entry<K, V>> insertionOrder) {
    @SuppressWarnings("unchecked") // assume any Comparable is Comparable<Self>
    Comparator<? super K> keyComparator = (Comparator<? super K>) Comparable::compareTo;
    sort(insertionOrder, Helpers.entryComparator(keyComparator));

 *
 * @author Bob Lee
 * @author Ben Yu
 * @author Gregory Kick
 * @since 10.0 (<a href="https://github.com/google/guava/wiki/Compatibility">mostly
 *     source-compatible</a> since 4.0)
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault
/*
 * The type parameter is <T> rather than <T extends @Nullable> so that we can use T in the

 *
 * @author Bob Lee
 * @author Ben Yu
 * @author Gregory Kick
 * @since 10.0 (<a href="https://github.com/google/guava/wiki/Compatibility">mostly
 *     source-compatible</a> since 4.0)
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault
/*
 * The type parameter is <T> rather than <T extends @Nullable> so that we can use T in the

   *
   * <p>An "IPv4 compatible", or "compat", address is one with 96 leading bits of zero, with the
   * remaining 32 bits interpreted as an IPv4 address. These are conventionally represented in
   * string literals as {@code "::192.168.0.1"}, though {@code "::c0a8:1"} is also considered an
   * IPv4 compatible address (and equivalent to {@code "::192.168.0.1"}).
   *