*
 * @author Jared Levy
 * @since 2.0
 */
@DoNotMock("Use ImmutableMultimap, HashMultimap, or another implementation")
@GwtCompatible
public interface Multimap<K extends @Nullable Object, V extends @Nullable Object> {
  // Query Operations

  /**
   * Returns the number of key-value pairs in this multimap.
   *

   * @return the replacement string, or {@code null} if no escaping was needed
   */
  public static @Nullable String computeReplacement(UnicodeEscaper escaper, int cp) {
    return stringOrNull(escaper.escape(cp));
  }

  private static @Nullable String stringOrNull(char @Nullable [] in) {
    return (in == null) ? null : new String(in);
  }

    return forwardMultiset();
  }

  @Override
  public @Nullable Entry<E> firstEntry() {
    return forwardMultiset().lastEntry();
  }

  @Override
  public @Nullable Entry<E> lastEntry() {
    return forwardMultiset().firstEntry();
  }

  abstract Iterator<Entry<E>> entryIterator();

  @Nullable private transient Set<Entry<E>> entrySet;

  @Override

  public E last() {
    return delegate.last();
  }

  @Override
  public @Nullable E lower(E e) {
    return delegate.lower(checkValid(e));
  }

  @Override
  public @Nullable E pollFirst() {
    return delegate.pollFirst();
  }

  @Override
  public @Nullable E pollLast() {
    return delegate.pollLast();
  }

  @Override
  public boolean remove(Object object) {

    @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();

  protected abstract ListeningExecutorService delegate();

  @Override
  public <T extends @Nullable Object> ListenableFuture<T> submit(Callable<T> task) {
    return delegate().submit(task);
  }

  @Override
  public ListenableFuture<?> submit(Runnable task) {
    return delegate().submit(task);
  }

  @Override
  public <T extends @Nullable Object> ListenableFuture<T> submit(
      Runnable task, @ParametricNullness T result) {

  public void testTransformEntrySetContains() {
    Map<@Nullable String, @Nullable Boolean> underlying = new HashMap<>();
    underlying.put("a", null);
    underlying.put("b", true);
    underlying.put(null, true);

    Map<@Nullable String, @Nullable Boolean> map =
        transformValues(
            underlying,
            new Function<@Nullable Boolean, @Nullable Boolean>() {
              @Override

  }

  public void testNullFriendlyTransform() {
    Iterator<@Nullable Integer> input = Arrays.<@Nullable Integer>asList(1, 2, null, 3).iterator();
    Iterator<String> result =
        Iterators.transform(
            input,
            new Function<@Nullable Integer, String>() {
              @Override
              public String apply(@Nullable Integer from) {
                return String.valueOf(from);
              }

     * in the value bucket (or vice versa).
     */
    private final transient @Nullable ImmutableMapEntry<K, V> nextInKeyBucket;

    NonTerminalImmutableMapEntry(
        K key, V value, @Nullable ImmutableMapEntry<K, V> nextInKeyBucket) {
      super(key, value);
      this.nextInKeyBucket = nextInKeyBucket;
    }

    @Override
    final @Nullable ImmutableMapEntry<K, V> getNextInKeyBucket() {
      return nextInKeyBucket;

    delegate().clear();
  }

  @Override
  public boolean containsEntry(@Nullable Object key, @Nullable Object value) {
    return delegate().containsEntry(key, value);
  }

  @Override
  public boolean containsKey(@Nullable Object key) {
    return delegate().containsKey(key);
  }

  @Override
  public boolean containsValue(@Nullable Object value) {
    return delegate().containsValue(value);
  }

  @Override