*       instance is unsafely published.
   * </ul>
   */
  private transient @Nullable ConcurrentHashMultiset<E> deserializationReplacement;

  /**
   * Creates a new, empty {@code ConcurrentHashMultiset} using the default initial capacity, load
   * factor, and concurrency settings.
   */
  public static <E> ConcurrentHashMultiset<E> create() {
    return create(new ConcurrentHashMap<>());
  }

  /**

   *       instance is unsafely published.
   * </ul>
   */
  private transient @Nullable ConcurrentHashMultiset<E> deserializationReplacement;

  /**
   * Creates a new, empty {@code ConcurrentHashMultiset} using the default initial capacity, load
   * factor, and concurrency settings.
   */
  public static <E> ConcurrentHashMultiset<E> create() {
    return create(new ConcurrentHashMap<>());
  }

  /**

    private final ContainsMultiset a;
    private final ConcurrentHashMultiset<?> z;

    ContainsBothWithContainsMultisetFirst(ContainsMultiset a, ConcurrentHashMultiset<?> z) {
      this.a = a;
      this.z = z;
    }
  }

  public void testCreate() {
    ConcurrentHashMultiset<Integer> multiset = ConcurrentHashMultiset.create();
    assertTrue(multiset.isEmpty());
    reserializeAndAssert(multiset);

import java.util.concurrent.ExecutorService;
import java.util.concurrent.Future;
import org.jspecify.annotations.NullUnmarked;
import org.jspecify.annotations.Nullable;

/**
 * Benchmarks for {@link ConcurrentHashMultiset}.
 *
 * @author mike nonemacher
 */
@NullUnmarked
public class ConcurrentHashMultisetBenchmark {
  @Param({"1", "2", "4", "8"})
  int threads;

  @Param({"3", "30", "300"})
  int size;

import static java.util.concurrent.Executors.newFixedThreadPool;

import com.google.common.annotations.GwtIncompatible;
import com.google.common.annotations.J2ktIncompatible;
import com.google.common.collect.ConcurrentHashMultiset;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.ImmutableMultiset;
import com.google.common.collect.Multiset;
import com.google.common.testing.TestLogHandler;
import java.util.Map;

import static java.util.concurrent.Executors.newFixedThreadPool;

import com.google.common.annotations.GwtIncompatible;
import com.google.common.annotations.J2ktIncompatible;
import com.google.common.collect.ConcurrentHashMultiset;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.ImmutableMultiset;
import com.google.common.collect.Multiset;
import com.google.common.testing.TestLogHandler;
import java.util.Map;

      }
    },
    ConcurrentHashMultisetImpl {
      @Override
      public <E extends Comparable<E>> Multiset<E> create(Collection<E> contents) {
        return ConcurrentHashMultiset.create(contents);
      }
    },
    ImmutableMultisetImpl {
      @Override
      public <E extends Comparable<E>> Multiset<E> create(Collection<E> contents) {

      }
    },
    ConcurrentHashMultisetImpl {
      @Override
      public <E extends Comparable<E>> Multiset<E> create(Collection<E> contents) {
        return ConcurrentHashMultiset.create(contents);
      }
    },
    ImmutableMultisetImpl {
      @Override
      public <E extends Comparable<E>> Multiset<E> create(Collection<E> contents) {

   * is used only by those methods, and it is never set in a "normal" instance.
   *
   * <p>For more background, see {@code ConcurrentHashMultiset.deserializationReplacement}.
   */
  private transient @Nullable ImmutableListMultimap<?, ?> deserializationReplacement;

  ImmutableListMultimap(ImmutableMap<K, ImmutableList<V>> map, int size) {

   * is used only by those methods, and it is never set in a "normal" instance.
   *
   * <p>For more background, see {@code ConcurrentHashMultiset.deserializationReplacement}.
   */
  private transient @Nullable ImmutableListMultimap<?, ?> deserializationReplacement;

  ImmutableListMultimap(ImmutableMap<K, ImmutableList<V>> map, int size) {