* elements.
 */
@GwtCompatible
final class ByFunctionOrdering<F extends @Nullable Object, T extends @Nullable Object>
    extends Ordering<F> implements Serializable {
  final Function<F, ? extends T> function;
  final Ordering<T> ordering;

  ByFunctionOrdering(Function<F, ? extends T> function, Ordering<T> ordering) {
    this.function = checkNotNull(function);

   * (you can omit the comparator if it is the natural order).
   */
  public <F extends @Nullable Object> Ordering<F> onResultOf(Function<F, ? extends T> function) {
    return new ByFunctionOrdering<>(function, this);
  }

  <T2 extends T> Ordering<Entry<T2, ?>> onKeys() {
    return onResultOf(Entry::getKey);
  }

  /**

   *
   * <p>The serialized output consists of the number of entries, first key, first value, second key,
   * second value, and so on.
   */
  static <K extends @Nullable Object, V extends @Nullable Object> void writeMap(
      Map<K, V> map, ObjectOutputStream stream) throws IOException {
    stream.writeInt(map.size());
    for (Map.Entry<K, V> entry : map.entrySet()) {

  public static <E extends @Nullable Object> List<E> copyToList(Iterable<? extends E> elements) {
    List<E> list = new ArrayList<>();
    addAll(list, elements);
    return list;
  }

  public static <E extends @Nullable Object> List<E> copyToList(E[] elements) {
    return copyToList(asList(elements));
  }

  // Clone of Sets.newLinkedHashSet

    runCollectionTests = false;
    return this;
  }

  @SuppressWarnings("rawtypes") // class literals
  @Override
  protected List<Class<? extends AbstractTester>> getTesters() {
    List<Class<? extends AbstractTester>> testers = new ArrayList<>();
    if (runCollectionTests) {
      testers.addAll(super.getTesters());
    }

    testers.add(QueueElementTester.class);

      Class<T> enumClass) {
    Map<String, WeakReference<? extends Enum<?>>> result = new HashMap<>();
    for (T enumInstance : EnumSet.allOf(enumClass)) {
      result.put(enumInstance.name(), new WeakReference<Enum<?>>(enumInstance));
    }
    enumConstantCache.put(enumClass, result);
    return result;
  }

      Iterator<? extends V> valueItr = values.iterator();
      return valueItr.hasNext() && Iterators.addAll(get(key), valueItr);
    }
  }

  @CanIgnoreReturnValue
  @Override
  public boolean putAll(Multimap<? extends K, ? extends V> multimap) {
    boolean changed = false;
    for (Entry<? extends K, ? extends V> entry : multimap.entries()) {
      changed |= put(entry.getKey(), entry.getValue());
    }
    return changed;
  }

    public Builder<K, V> put(Entry<? extends K, ? extends V> entry) {
      return put(entry.getKey(), entry.getValue());
    }

    /**
     * Adds entries to the built multimap.
     *
     * @since 19.0
     */
    @CanIgnoreReturnValue
    public Builder<K, V> putAll(Iterable<? extends Entry<? extends K, ? extends V>> entries) {
      for (Entry<? extends K, ? extends V> entry : entries) {
        put(entry);

/**
 * Implementation of {@link Multimaps#filterKeys(Multimap, Predicate)}.
 *
 * @author Louis Wasserman
 */
@GwtCompatible
class FilteredKeyMultimap<K extends @Nullable Object, V extends @Nullable Object>
    extends AbstractMultimap<K, V> implements FilteredMultimap<K, V> {
  final Multimap<K, V> unfiltered;
  final Predicate<? super K> keyPredicate;

/**
 * Implementation of {@link Multimaps#filterKeys(Multimap, Predicate)}.
 *
 * @author Louis Wasserman
 */
@GwtCompatible
class FilteredKeyMultimap<K extends @Nullable Object, V extends @Nullable Object>
    extends AbstractMultimap<K, V> implements FilteredMultimap<K, V> {
  final Multimap<K, V> unfiltered;
  final Predicate<? super K> keyPredicate;