*/
  @GwtIncompatible
  @J2ktIncompatible
    private void writeObject(ObjectOutputStream stream) throws IOException {
    stream.defaultWriteObject();
    stream.writeObject(elementSet().comparator());
    Serialization.writeMultiset(this, stream);
  }

  @J2ktIncompatible
  @GwtIncompatible
    private void readObject(ObjectInputStream stream) throws IOException, ClassNotFoundException {

    @Override
    public int count(@Nullable Object element) {
      Collection<V> values = map.get(element);
      return (values == null) ? 0 : values.size();
    }

    @Override
    public ImmutableSet<K> elementSet() {
      return keySet();
    }

    @Override
    public int size() {
      return ImmutableMultimap.this.size();
    }

    @Override
    Multiset.Entry<K> getEntry(int index) {

    assertFalse(multimapView.containsKey("bar"));
    assertFalse(map.containsKey("bar"));
    assertEquals(map.keySet(), multimapView.keySet());
    assertEquals(map.keySet(), multimapView.keys().elementSet());
    assertThat(multimapView.keys()).contains("foo");
    assertThat(multimapView.values()).contains(1);
    assertThat(multimapView.entries()).contains(Maps.immutableEntry("foo", 1));

   */
  @GwtIncompatible
  @J2ktIncompatible
    private void writeObject(ObjectOutputStream stream) throws IOException {
    stream.defaultWriteObject();
    stream.writeObject(elementSet().comparator());
    Serialization.writeMultiset(this, stream);
  }

  @J2ktIncompatible
  @GwtIncompatible
    private void readObject(ObjectInputStream stream) throws IOException, ClassNotFoundException {

  }

  static boolean removeAllImpl(Set<?> set, Collection<?> collection) {
    checkNotNull(collection); // for GWT
    if (collection instanceof Multiset) {
      collection = ((Multiset<?>) collection).elementSet();
    }
    /*
     * AbstractSet.removeAll(List) has quadratic behavior if the list size
     * is just more than the set's size.  We augment the test by

        }
      }
      return oldCount;
    }

    @Override
    public void clear() {
      multimap.clear();
    }

    @Override
    public Set<K> elementSet() {
      return multimap.keySet();
    }

    @Override
    Iterator<K> elementIterator() {
      throw new AssertionError("should never be called");
    }
  }