/**
 * GWT implementation of {@link ImmutableSet} that forwards to another {@code Set} implementation.
 *
 * @author Hayward Chan
 */
@ElementTypesAreNonnullByDefault
@SuppressWarnings("serial") // Serialization only done in GWT.
public abstract class ForwardingImmutableSet<E> extends ImmutableSet<E> {
  private final transient Set<E> delegate;

  ForwardingImmutableSet(Set<E> delegate) {

import java.util.HashMap;

/**
 * GWT emulation of {@link RegularImmutableBiMap}.
 *
 * @author Jared Levy
 * @author Hayward Chan
 */
@ElementTypesAreNonnullByDefault
@SuppressWarnings("serial")
class RegularImmutableBiMap<K, V> extends ImmutableBiMap<K, V> {
  static final RegularImmutableBiMap<Object, Object> EMPTY =
      new RegularImmutableBiMap<Object, Object>();

import com.google.common.annotations.J2ktIncompatible;
import javax.annotation.CheckForNull;

/**
 * A descending wrapper around an {@code ImmutableSortedMultiset}
 *
 * @author Louis Wasserman
 */
@SuppressWarnings("serial") // uses writeReplace, not default serialization
@GwtIncompatible
@ElementTypesAreNonnullByDefault
final class DescendingImmutableSortedMultiset<E> extends ImmutableSortedMultiset<E> {

import com.google.common.annotations.J2ktIncompatible;
import javax.annotation.CheckForNull;

/**
 * A descending wrapper around an {@code ImmutableSortedMultiset}
 *
 * @author Louis Wasserman
 */
@SuppressWarnings("serial") // uses writeReplace, not default serialization
@GwtIncompatible
@ElementTypesAreNonnullByDefault
final class DescendingImmutableSortedMultiset<E> extends ImmutableSortedMultiset<E> {

/**
 * Implementation of {@link ImmutableSet} with exactly one element.
 *
 * @author Kevin Bourrillion
 * @author Nick Kralevich
 */
@GwtCompatible(serializable = true, emulated = true)
@SuppressWarnings("serial") // uses writeReplace(), not default serialization
@ElementTypesAreNonnullByDefault
final class SingletonImmutableSet<E> extends ImmutableSet<E> {
  // We deliberately avoid caching the asList and hashCode here, to ensure that with

/**
 * Implementation of {@link ImmutableSet} with two or more elements.
 *
 * @author Kevin Bourrillion
 */
@GwtCompatible(serializable = true, emulated = true)
@SuppressWarnings("serial") // uses writeReplace(), not default serialization
@ElementTypesAreNonnullByDefault
final class RegularImmutableSet<E> extends ImmutableSet<E> {
  private static final Object[] EMPTY_ARRAY = new Object[0];

import java.util.Comparator;
import javax.annotation.CheckForNull;

/**
 * An immutable sorted multiset with one or more distinct elements.
 *
 * @author Louis Wasserman
 */
@SuppressWarnings("serial") // uses writeReplace, not default serialization
@GwtIncompatible
@ElementTypesAreNonnullByDefault
final class RegularImmutableSortedMultiset<E> extends ImmutableSortedMultiset<E> {

/**
 * Implementation of {@link ImmutableMultiset} with zero or more elements.
 *
 * @author Jared Levy
 * @author Louis Wasserman
 */
@GwtCompatible(emulated = true, serializable = true)
@SuppressWarnings("serial") // uses writeReplace(), not default serialization
@ElementTypesAreNonnullByDefault
class RegularImmutableMultiset<E> extends ImmutableMultiset<E> {
  static final RegularImmutableMultiset<Object> EMPTY =

import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Bimap with zero or more mappings.
 *
 * @author Louis Wasserman
 */
@GwtCompatible(serializable = true, emulated = true)
@SuppressWarnings("serial") // uses writeReplace(), not default serialization
@ElementTypesAreNonnullByDefault
final class RegularImmutableBiMap<K, V> extends ImmutableBiMap<K, V> {

import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Unit test for {@link AbstractMultiset}.
 *
 * @author Kevin Bourrillion
 * @author Louis Wasserman
 */
@SuppressWarnings("serial") // No serialization is used in this test
@GwtCompatible(emulated = true)
@ElementTypesAreNonnullByDefault
public class SimpleAbstractMultisetTest extends TestCase {
  @J2ktIncompatible
  @GwtIncompatible // suite