* #elementSet()}. Override those methods for better performance.
 *
 * @author Kevin Bourrillion
 * @author Louis Wasserman
 */
@GwtCompatible
abstract class AbstractMultiset<E extends @Nullable Object> extends AbstractCollection<E>
    implements Multiset<E> {
  // Query Operations

  @Override
  public boolean isEmpty() {
    return entrySet().isEmpty();
  }

  @Override

 * writeObject} methods.
 *
 * @author Kevin Bourrillion
 */
@GwtCompatible
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;

  /*

import junit.framework.Test;
import junit.framework.TestCase;
import junit.framework.TestSuite;
import org.jspecify.annotations.NullMarked;
import org.jspecify.annotations.Nullable;

/**
 * Unit test for {@link AbstractMultiset}.
 *
 * @author Kevin Bourrillion
 * @author Louis Wasserman
 */
@SuppressWarnings("serial") // No serialization is used in this test
@GwtCompatible
@NullMarked

 * #elementSet()}. Override those methods for better performance.
 *
 * @author Louis Wasserman
 */
@GwtCompatible
abstract class AbstractSortedMultiset<E extends @Nullable Object> extends AbstractMultiset<E>
    implements SortedMultiset<E> {
  private final Comparator<? super E> comparator;

  // needed for serialization
  @SuppressWarnings("unchecked")
  AbstractSortedMultiset() {

 * @since 2.0
 */
@GwtCompatible
@J2ktIncompatible
@SuppressWarnings("EnumOrdinal") // This is one of the low-level utilities where it's suitable.
public final class EnumMultiset<E extends Enum<E>> extends AbstractMultiset<E>
    implements Serializable {
  /** Creates an empty {@code EnumMultiset}. */
  public static <E extends Enum<E>> EnumMultiset<E> create(Class<E> type) {
    return new EnumMultiset<>(type);
  }

  /**

 * writeObject} methods.
 *
 * @author Kevin Bourrillion
 */
@GwtCompatible
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 Cliff L. Biffle
 * @author mike nonemacher
 * @since 2.0
 */
@J2ktIncompatible
@GwtIncompatible
public final class ConcurrentHashMultiset<E> extends AbstractMultiset<E> implements Serializable {

  /*
   * The ConcurrentHashMultiset's atomic operations are implemented primarily in terms of
   * AtomicInteger's atomic operations, with some help from ConcurrentMap's atomic operations on

    }
  }

  /**
   * An {@link AbstractMultiset} with additional default implementations, some of them linear-time
   * implementations in terms of {@code elementSet} and {@code entrySet}.
   */
  private abstract static class ViewMultiset<E extends @Nullable Object>
      extends AbstractMultiset<E> {
    @Override
    public int size() {
      return linearTimeSizeImpl(this);

    }
  }

  /**
   * An {@link AbstractMultiset} with additional default implementations, some of them linear-time
   * implementations in terms of {@code elementSet} and {@code entrySet}.
   */
  private abstract static class ViewMultiset<E extends @Nullable Object>
      extends AbstractMultiset<E> {
    @Override
    public int size() {
      return linearTimeSizeImpl(this);

    successor(b, c);
  }

  /*
   * TODO(jlevy): Decide whether entrySet() should return entries with an equals() method that
   * calls the comparator to compare the two keys. If that change is made,
   * AbstractMultiset.equals() can simply check whether two multisets have equal entry sets.
   */

  /**
   * @serialData the comparator, the number of distinct elements, the first element, its count, the