*     {@code double}) in the proper order.
   */
  private void writeObject(ObjectOutputStream s) throws IOException {
    s.defaultWriteObject();

    // Write out array length
    int length = length();
    s.writeInt(length);

    // Write out all elements in the proper order.
    for (int i = 0; i < length; i++) {

      Arrays.fill(requireEntries(), 0, size, 0);
      this.size = 0;
    }
  }

  @J2ktIncompatible
  private void writeObject(ObjectOutputStream stream) throws IOException {
    stream.defaultWriteObject();
    stream.writeInt(size());
    for (E e : this) {
      stream.writeObject(e);
    }
  }

  @SuppressWarnings("unchecked")
  @J2ktIncompatible

   *     and the entries in order
   */
  @GwtIncompatible
  @J2ktIncompatible
    private void writeObject(ObjectOutputStream stream) throws IOException {
    stream.defaultWriteObject();
    stream.writeInt(keySet().size());
    for (K key : keySet()) {
      stream.writeObject(key);
    }
    stream.writeInt(size());
    for (Entry<K, V> entry : entries()) {

   *     values for that key, and the key's values
   */
  @GwtIncompatible
  @J2ktIncompatible
    private void writeObject(ObjectOutputStream stream) throws IOException {
    stream.defaultWriteObject();
    Serialization.writeMultimap(this, stream);
  }

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

   *     values for that key, and the key's values
   */
  @GwtIncompatible
  @J2ktIncompatible
    private void writeObject(ObjectOutputStream stream) throws IOException {
    stream.defaultWriteObject();
    Serialization.writeMultimap(this, stream);
  }

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

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

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

   *     from the entries() ordering
   */
  @GwtIncompatible
  @J2ktIncompatible
    private void writeObject(ObjectOutputStream stream) throws IOException {
    stream.defaultWriteObject();
    stream.writeInt(size());
    for (Entry<K, V> entry : entries()) {
      stream.writeObject(entry.getKey());
      stream.writeObject(entry.getValue());
    }
  }

  @GwtIncompatible

   *     values for that key, and the key's values
   */
  @GwtIncompatible
  @J2ktIncompatible
    private void writeObject(ObjectOutputStream stream) throws IOException {
    stream.defaultWriteObject();
    stream.writeObject(valueComparator());
    Serialization.writeMultimap(this, stream);
  }

  @Nullable Comparator<? super V> valueComparator() {
    return emptySet instanceof ImmutableSortedSet

      Arrays.fill(requireEntries(), 0, size, 0);
      this.size = 0;
    }
  }

  @J2ktIncompatible
  private void writeObject(ObjectOutputStream stream) throws IOException {
    stream.defaultWriteObject();
    stream.writeInt(size());
    Iterator<Entry<K, V>> entryIterator = entrySetIterator();
    while (entryIterator.hasNext()) {
      Entry<K, V> e = entryIterator.next();

   *     values for that key, and the key's values
   */
  @GwtIncompatible
  @J2ktIncompatible
    private void writeObject(ObjectOutputStream stream) throws IOException {
    stream.defaultWriteObject();
    stream.writeObject(valueComparator());
    Serialization.writeMultimap(this, stream);
  }

  @Nullable Comparator<? super V> valueComparator() {
    return emptySet instanceof ImmutableSortedSet