* <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(
      final Multiset<? extends E> multiset1, final Multiset<? extends E> multiset2) {
    checkNotNull(multiset1);
    checkNotNull(multiset2);

      @Override
      protected Multiset<String> create(String[] elements) {
        Multiset<String> multiset1 = LinkedHashMultiset.create();
        Multiset<String> multiset2 = LinkedHashMultiset.create();
        multiset1.add("equalIn1");
        multiset1.add("fewerIn1");
        multiset2.add("equalIn1");
        multiset2.add("fewerIn1", 3);
        multiset2.add("onlyIn2", 2);
        for (int i = 0; i < elements.length; i++) {

      @Override
      protected Multiset<String> create(String[] elements) {
        Multiset<String> multiset1 = LinkedHashMultiset.create();
        Multiset<String> multiset2 = LinkedHashMultiset.create();
        multiset1.add("equalIn1");
        multiset1.add("fewerIn1");
        multiset2.add("equalIn1");
        multiset2.add("fewerIn1", 3);
        multiset2.add("onlyIn2", 2);
        for (int i = 0; i < elements.length; i++) {

    assertThat(multiset).isEmpty();
  }

  public void testRemoveOccurrencesIterableEmpty() {
    Multiset<String> multiset = HashMultiset.create();
    Iterable<String> toRemove = Arrays.asList("a", "b", "a");
    assertFalse(Multisets.removeOccurrences(multiset, toRemove));
    assertTrue(multiset.isEmpty());
  }

  public void testRemoveOccurrencesMultisetEmpty() {

    assertThat(multiset).isEmpty();
  }

  public void testRemoveOccurrencesIterableEmpty() {
    Multiset<String> multiset = HashMultiset.create();
    Iterable<String> toRemove = Arrays.asList("a", "b", "a");
    assertFalse(Multisets.removeOccurrences(multiset, toRemove));
    assertTrue(multiset.isEmpty());
  }

  public void testRemoveOccurrencesMultisetEmpty() {

    assertEquals(expected, actual);
  }

  public void testForEachEntryDuplicates() {
    initThreeCopies();
    List<Entry<E>> expected = Collections.singletonList(Multisets.immutableEntry(e0(), 3));
    List<Entry<E>> actual = new ArrayList<>();
    getMultiset()
        .forEachEntry((element, count) -> actual.add(Multisets.immutableEntry(element, count)));

   * and if, for each element, the two multisets have the same count.
   */
  @Override
  public final boolean equals(@CheckForNull Object object) {
    return Multisets.equalsImpl(this, object);
  }

  /**
   * {@inheritDoc}
   *
   * <p>This implementation returns the hash code of {@link Multiset#entrySet()}.
   */
  @Override

    Multiset<K> keys = multimap().keys();
    assertEquals(2, keys.count(k0()));
    assertEquals(1, keys.count(k1()));
    assertEquals(3, keys.size());
    assertContainsAllOf(keys, k0(), k1());
    assertContainsAllOf(
        keys.entrySet(), Multisets.immutableEntry(k0(), 2), Multisets.immutableEntry(k1(), 1));
  }

  @MapFeature.Require(ALLOWS_NULL_KEY_QUERIES)

    Multiset<K> keys = multimap().keys();
    assertEquals(2, keys.count(k0()));
    assertEquals(1, keys.count(k1()));
    assertEquals(3, keys.size());
    assertContainsAllOf(keys, k0(), k1());
    assertContainsAllOf(
        keys.entrySet(), Multisets.immutableEntry(k0(), 2), Multisets.immutableEntry(k1(), 1));
  }

  @MapFeature.Require(ALLOWS_NULL_KEY_QUERIES)

  private static final int ARRAY_SIZE = 0x10000;
  List<Multiset<Integer>> multisets = new ArrayList<>(0x10000);
  int[] queries = new int[ARRAY_SIZE];

  @BeforeExperiment
  void setUp() {
    Random random = new Random();
    multisets.clear();
    for (int i = 0; i < ARRAY_SIZE; i++) {
      HashMultiset<Integer> multiset = HashMultiset.<Integer>create();
      multisets.add(multiset);
      queries[i] = random.nextInt();