* multiset1}, with repeated occurrences of the same element appearing consecutively.
   *
   * <p>Results are undefined if {@code multiset1} and {@code multiset2} are based on different
   * equivalence relations (as {@code HashMultiset} and {@code TreeMultiset} are).
   *
   * @since 14.0
   */
  public static <E extends @Nullable Object> Multiset<E> union(
      Multiset<? extends E> multiset1, Multiset<? extends E> multiset2) {

   * multiset1}, with repeated occurrences of the same element appearing consecutively.
   *
   * <p>Results are undefined if {@code multiset1} and {@code multiset2} are based on different
   * equivalence relations (as {@code HashMultiset} and {@code TreeMultiset} are).
   *
   * @since 14.0
   */
  public static <E extends @Nullable Object> Multiset<E> union(
      Multiset<? extends E> multiset1, Multiset<? extends E> multiset2) {

  @Generates
  static <E> Multiset<E> generateMultiset(@Nullable E freshElement) {
    return generateHashMultiset(freshElement);
  }

  @Generates
  static <E> HashMultiset<E> generateHashMultiset(@Nullable E freshElement) {
    HashMultiset<E> multiset = HashMultiset.create();
    multiset.add(freshElement);
    return multiset;
  }

  @Generates

import com.google.common.collect.BiMap;
import com.google.common.collect.HashBasedTable;
import com.google.common.collect.HashBiMap;
import com.google.common.collect.HashMultimap;
import com.google.common.collect.HashMultiset;
import com.google.common.collect.ImmutableBiMap;
import com.google.common.collect.ImmutableCollection;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableListMultimap;

  @Generates
  static <E> Multiset<E> generateMultiset(@Nullable E freshElement) {
    return generateHashMultiset(freshElement);
  }

  @Generates
  static <E> HashMultiset<E> generateHashMultiset(@Nullable E freshElement) {
    HashMultiset<E> multiset = HashMultiset.create();
    multiset.add(freshElement);
    return multiset;
  }

  @Generates

        return OldConcurrentHashMultiset.create();
      }
    },
    SYNCHRONIZED_MULTISET() {
      @Override
      Multiset<Integer> get() {
        return Synchronized.multiset(HashMultiset.<Integer>create(), null);
      }
    },
    ;

    abstract Multiset<Integer> get();
  }

  /**
   * Duplication of the old version of ConcurrentHashMultiset (with some unused stuff removed, like

import com.google.common.collect.BiMap;
import com.google.common.collect.HashBasedTable;
import com.google.common.collect.HashBiMap;
import com.google.common.collect.HashMultimap;
import com.google.common.collect.HashMultiset;
import com.google.common.collect.ImmutableBiMap;
import com.google.common.collect.ImmutableCollection;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableListMultimap;

    Multiset<String> c = HashMultiset.create();
    Multiset<String> multiset = ImmutableSortedMultiset.copyOf(c);
    assertTrue(multiset.isEmpty());
  }

  public void testCopyOf_multiset_oneElement() {
    Multiset<String> c = HashMultiset.create(asList("a"));
    Multiset<String> multiset = ImmutableSortedMultiset.copyOf(c);
    assertEquals(HashMultiset.create(asList("a")), multiset);
  }

    Multiset<String> c = HashMultiset.create();
    Multiset<String> multiset = ImmutableMultiset.copyOf(c);
    assertTrue(multiset.isEmpty());
  }

  public void testCopyOf_multiset_oneElement() {
    Multiset<String> c = HashMultiset.create(asList("a"));
    Multiset<String> multiset = ImmutableMultiset.copyOf(c);
    assertEquals(HashMultiset.create(asList("a")), multiset);
  }

    Multiset<String> c = HashMultiset.create();
    Multiset<String> multiset = ImmutableSortedMultiset.copyOf(c);
    assertTrue(multiset.isEmpty());
  }

  public void testCopyOf_multiset_oneElement() {
    Multiset<String> c = HashMultiset.create(asList("a"));
    Multiset<String> multiset = ImmutableSortedMultiset.copyOf(c);
    assertEquals(HashMultiset.create(asList("a")), multiset);
  }