* of distinct keys in a multimap serialized by {@link #writeMultimap(Multimap,
   * ObjectOutputStream)}.
   */
  static int readCount(ObjectInputStream stream) throws IOException {
    return stream.readInt();
  }

  /**
   * Stores the contents of a map in an output stream, as part of serialization. It does not support
   * concurrent maps whose content may change while the method is running.
   *

    assertThrows(IllegalStateException.class, () -> in.readInt());
  }

  public void testNewDataInput_normal() {
    ByteArrayDataInput in = ByteStreams.newDataInput(bytes);
    assertEquals(0x12345678, in.readInt());
    assertEquals(0x76543210, in.readInt());
    assertThrows(IllegalStateException.class, () -> in.readInt());
  }

  public void testNewDataInput_readFully() {

   * Reads an integer as specified by {@link DataInputStream#readInt()}, except using little-endian
   * byte order.
   *
   * @return the next four bytes of the input stream, interpreted as an {@code int} in little-endian
   *     byte order
   * @throws IOException if an I/O error occurs
   */
  @CanIgnoreReturnValue // to skip some bytes
  @Override
  public int readInt() throws IOException {
    byte b1 = readAndCheckByte();

    assertEquals(200, in.readUnsignedByte());
    assertEquals('\u6100', in.readChar());
    assertEquals(-12150, in.readShort());
    assertEquals(20675, in.readUnsignedShort());
    assertEquals(0xBEBAFECA, in.readInt());
    assertEquals(0xBEBAFECAEFBEADDEL, in.readLong());
    assertEquals("Herby Derby", in.readUTF());
    assertEquals(0xBEBAFECA, Float.floatToIntBits(in.readFloat()));

    assertEquals(200, in.readUnsignedByte());
    assertEquals('\u6100', in.readChar());
    assertEquals(-12150, in.readShort());
    assertEquals(20675, in.readUnsignedShort());
    assertEquals(0xBEBAFECA, in.readInt());
    assertEquals(0xBEBAFECAEFBEADDEL, in.readLong());
    assertEquals("Herby Derby", in.readUTF());
    assertEquals(0xBEBAFECA, Float.floatToIntBits(in.readFloat()));

    valueSetCapacity = DEFAULT_VALUE_SET_CAPACITY;
    int distinctKeys = stream.readInt();
    Map<K, Collection<V>> map = Platform.newLinkedHashMapWithExpectedSize(12);
    for (int i = 0; i < distinctKeys; i++) {
      @SuppressWarnings("unchecked")
      K key = (K) stream.readObject();
      map.put(key, createCollection(key));
    }
    int entries = stream.readInt();
    for (int i = 0; i < entries; i++) {

    valueSetCapacity = DEFAULT_VALUE_SET_CAPACITY;
    int distinctKeys = stream.readInt();
    Map<K, Collection<V>> map = Platform.newLinkedHashMapWithExpectedSize(12);
    for (int i = 0; i < distinctKeys; i++) {
      @SuppressWarnings("unchecked")
      K key = (K) stream.readObject();
      map.put(key, createCollection(key));
    }
    int entries = stream.readInt();
    for (int i = 0; i < entries; i++) {

  private void readObject(java.io.ObjectInputStream s)
      throws java.io.IOException, ClassNotFoundException {
    s.defaultReadObject();

    int length = s.readInt();
    ImmutableLongArray.Builder builder = ImmutableLongArray.builder();
    for (int i = 0; i < length; i++) {
      builder.add(doubleToRawLongBits(s.readDouble()));
    }

  private void readObject(java.io.ObjectInputStream s)
      throws java.io.IOException, ClassNotFoundException {
    s.defaultReadObject();

    int length = s.readInt();
    ImmutableLongArray.Builder builder = ImmutableLongArray.builder();
    for (int i = 0; i < length; i++) {
      builder.add(doubleToRawLongBits(s.readDouble()));
    }

  @J2ktIncompatible
  private void readObject(ObjectInputStream stream) throws IOException, ClassNotFoundException {
    stream.defaultReadObject();
    keyToKeyList = CompactLinkedHashMap.create();
    int size = stream.readInt();
    for (int i = 0; i < size; i++) {
      @SuppressWarnings("unchecked") // reading data stored by writeObject
      K key = (K) stream.readObject();