* writeObject} methods.
 *
 * @author Kevin Bourrillion
 */
@GwtCompatible(emulated = true)
@ElementTypesAreNonnullByDefault
abstract class AbstractMapBasedMultiset<E extends @Nullable Object> extends AbstractMultiset<E>
    implements Serializable {
  // TODO(lowasser): consider overhauling this back to Map<E, Integer>
  private transient Map<E, Count> backingMap;

  /*

 * @author Kevin Bourrillion
 */
@GwtCompatible(emulated = true)
@ElementTypesAreNonnullByDefault
abstract class AbstractMapBasedMultiset<E extends @Nullable Object> extends AbstractMultiset<E>
    implements Serializable {

  transient ObjectCountHashMap<E> backingMap;
  transient long size;

  AbstractMapBasedMultiset(int distinctElements) {
    backingMap = newBackingMap(distinctElements);
  }

 * @author Jared Levy
 * @since 2.0
 */
@GwtCompatible(serializable = true, emulated = true)
@ElementTypesAreNonnullByDefault
public final class LinkedHashMultiset<E extends @Nullable Object>
    extends AbstractMapBasedMultiset<E> {

  /** Creates a new, empty {@code LinkedHashMultiset} using the default initial capacity. */
  public static <E extends @Nullable Object> LinkedHashMultiset<E> create() {

import java.util.EnumMap;
import java.util.Iterator;

@GwtCompatible(emulated = true)
@J2ktIncompatible
@ElementTypesAreNonnullByDefault
public final class EnumMultiset<E extends Enum<E>> extends AbstractMapBasedMultiset<E>
    implements Serializable {
  public static <E extends Enum<E>> EnumMultiset<E> create(Class<E> type) {
    return new EnumMultiset<>(new EnumMap<E, Count>(type));
  }

 * @author Jared Levy
 * @since 2.0
 */
@GwtCompatible(serializable = true, emulated = true)
@ElementTypesAreNonnullByDefault
public final class HashMultiset<E extends @Nullable Object> extends AbstractMapBasedMultiset<E> {

  /** Creates a new, empty {@code HashMultiset} using the default initial capacity. */
  public static <E extends @Nullable Object> HashMultiset<E> create() {
    return create(ObjectCountHashMap.DEFAULT_SIZE);

 * @author Jared Levy
 * @since 2.0
 */
@GwtCompatible(serializable = true, emulated = true)
@ElementTypesAreNonnullByDefault
public final class HashMultiset<E extends @Nullable Object> extends AbstractMapBasedMultiset<E> {

  /** Creates a new, empty {@code HashMultiset} using the default initial capacity. */
  public static <E extends @Nullable Object> HashMultiset<E> create() {
    return new HashMultiset<>();
  }

  /**

    // It'd be nice if we could specialize for ImmutableMultiset here without also retaining
    // its code when it's not in scope...
    if (elements instanceof AbstractMapBasedMultiset) {
      return addAllImpl(self, (AbstractMapBasedMultiset<? extends E>) elements);
    } else if (elements.isEmpty()) {
      return false;
    } else {
      for (Multiset.Entry<? extends E> entry : elements.entrySet()) {

      if (multiset instanceof RegularImmutableMultiset) {
        return ((RegularImmutableMultiset<T>) multiset).contents;
      } else if (multiset instanceof AbstractMapBasedMultiset) {
        return ((AbstractMapBasedMultiset<T>) multiset).backingMap;
      } else {
        return null;
      }
    }

    /**