* <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);

  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();

   */
  protected class StandardElementSet extends Multisets.ElementSet<E> {
    /** Constructor for use by subclasses. */
    public StandardElementSet() {}

    @Override
    Multiset<E> multiset() {
      return ForwardingMultiset.this;
    }

    @Override
    public Iterator<E> iterator() {
      return Multisets.elementIterator(multiset().entrySet().iterator());
    }
  }

  /**

    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() {

 */

package com.google.common.collect;

import com.google.common.collect.Multisets.UnmodifiableMultiset;
import java.util.Collections;
import java.util.Comparator;
import java.util.SortedSet;
import javax.annotation.CheckForNull;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Implementation of {@link Multisets#unmodifiableSortedMultiset(SortedMultiset)} for GWT.
 *
 * @author Louis Wasserman
 */

    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)

   * 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

  @Override
  @CheckForNull
  public Entry<E> pollFirstEntry() {
    Iterator<Entry<E>> entryIterator = entryIterator();
    if (entryIterator.hasNext()) {
      Entry<E> result = entryIterator.next();
      result = Multisets.immutableEntry(result.getElement(), result.getCount());
      entryIterator.remove();
      return result;
    }
    return null;
  }

  @Override
  @CheckForNull
  public Entry<E> pollLastEntry() {

import java.util.SortedSet;
import javax.annotation.CheckForNull;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * A sorted multiset which forwards all its method calls to another sorted multiset. Subclasses
 * should override one or more methods to modify the behavior of the backing multiset as desired per
 * the <a href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>.
 *