private static class SynchronizedMultimap<K extends @Nullable Object, V extends @Nullable Object>
      extends SynchronizedObject implements Multimap<K, V> {
    transient @Nullable Set<K> keySet;
    transient @Nullable Collection<V> valuesCollection;
    transient @Nullable Collection<Map.Entry<K, V>> entries;
    transient @Nullable Map<K, Collection<V>> asMap;
    transient @Nullable Multiset<K> keys;

    @SuppressWarnings("unchecked")

  private static class SynchronizedMultimap<K extends @Nullable Object, V extends @Nullable Object>
      extends SynchronizedObject implements Multimap<K, V> {
    transient @Nullable Set<K> keySet;
    transient @Nullable Collection<V> valuesCollection;
    transient @Nullable Collection<Map.Entry<K, V>> entries;
    transient @Nullable Map<K, Collection<V>> asMap;
    transient @Nullable Multiset<K> keys;

    @SuppressWarnings("unchecked")

   *
   * @since 20.0 (varargs overload since 2.0)
   */
  @CanIgnoreReturnValue
  public static <T> T checkNotNull(
      @Nullable T reference,
      String errorMessageTemplate,
      @Nullable Object p1,
      @Nullable Object p2,
      @Nullable Object p3,
      @Nullable Object p4) {
    if (reference == null) {
      throw new NullPointerException(Platform.lenientFormat(errorMessageTemplate, p1, p2, p3, p4));

  private static class UnmodifiableMultimap<K extends @Nullable Object, V extends @Nullable Object>
      extends ForwardingMultimap<K, V> implements Serializable {
    final Multimap<K, V> delegate;
    @LazyInit transient @Nullable Collection<Entry<K, V>> entries;
    @LazyInit transient @Nullable Multiset<K> keys;
    @LazyInit transient @Nullable Set<K> keySet;
    @LazyInit transient @Nullable Collection<V> values;

  private static class UnmodifiableMultimap<K extends @Nullable Object, V extends @Nullable Object>
      extends ForwardingMultimap<K, V> implements Serializable {
    final Multimap<K, V> delegate;
    @LazyInit transient @Nullable Collection<Entry<K, V>> entries;
    @LazyInit transient @Nullable Multiset<K> keys;
    @LazyInit transient @Nullable Set<K> keySet;
    @LazyInit transient @Nullable Collection<V> values;

   * @throws IllegalArgumentException if {@code size} is nonpositive
   */
  public static <T extends @Nullable Object>
      UnmodifiableIterator<List<@Nullable T>> paddedPartition(Iterator<T> iterator, int size) {
    return partitionImpl(iterator, size, true);
  }

  private static <T extends @Nullable Object> UnmodifiableIterator<List<@Nullable T>> partitionImpl(
      Iterator<T> iterator, int size, boolean pad) {
    checkNotNull(iterator);

   * @throws IllegalArgumentException if {@code size} is nonpositive
   */
  public static <T extends @Nullable Object>
      UnmodifiableIterator<List<@Nullable T>> paddedPartition(Iterator<T> iterator, int size) {
    return partitionImpl(iterator, size, true);
  }

  private static <T extends @Nullable Object> UnmodifiableIterator<List<@Nullable T>> partitionImpl(
      Iterator<T> iterator, int size, boolean pad) {
    checkNotNull(iterator);

    public @Nullable E higher(@ParametricNullness E e) {
      return delegate.higher(e);
    }

    @Override
    public @Nullable E pollFirst() {
      throw new UnsupportedOperationException();
    }

    @Override
    public @Nullable E pollLast() {
      throw new UnsupportedOperationException();
    }

    @LazyInit private transient @Nullable UnmodifiableNavigableSet<E> descendingSet;

   *
   * @since 20.0 (varargs overload since 2.0)
   */
  @CanIgnoreReturnValue
  public static <T> T checkNotNull(
      @Nullable T reference,
      String errorMessageTemplate,
      @Nullable Object p1,
      @Nullable Object p2,
      @Nullable Object p3,
      @Nullable Object p4) {
    if (reference == null) {
      throw new NullPointerException(Platform.lenientFormat(errorMessageTemplate, p1, p2, p3, p4));

    @Nullable Segment<K, V, E, S> currentSegment;
    @Nullable AtomicReferenceArray<E> currentTable;
    @Nullable E nextEntry;
    @Nullable WriteThroughEntry nextExternal;
    @Nullable WriteThroughEntry lastReturned;

    HashIterator() {
      nextSegmentIndex = segments.length - 1;
      nextTableIndex = -1;
      advance();
    }

    @Override
    public abstract T next();