private String leave() {
    return "leave";
  }

  public final void testMutualExclusion() throws Exception {
    thread1.callAndAssertReturns(enter());
    thread2.callAndAssertBlocks(enter());
    thread1.callAndAssertReturns(leave());
    thread2.assertPriorCallReturns(enter());
  }

  public final void testTryEnter() throws Exception {
    thread1.callAndAssertReturns(true, tryEnter());

    verifyOccupiedMethodsInAnotherThread(monitor, false, false, 0);
    monitor.enter();
    try {
      verifyOccupiedMethodsInCurrentThread(monitor, true, true, 1);
      verifyOccupiedMethodsInAnotherThread(monitor, true, false, 0);
      monitor.enter();
      try {
        verifyOccupiedMethodsInCurrentThread(monitor, true, true, 2);

  public static class Chars extends SampleElements<Character> {
    public Chars() {
      // elements aren't sorted, to better test SortedSet iteration ordering
      super('b', 'a', 'c', 'd', 'e');
    }
  }

  public static class Enums extends SampleElements<AnEnum> {
    public Enums() {
      // elements aren't sorted, to better test SortedSet iteration ordering
      super(AnEnum.B, AnEnum.A, AnEnum.C, AnEnum.D, AnEnum.E);
    }
  }

  public static class Chars extends SampleElements<Character> {
    public Chars() {
      // elements aren't sorted, to better test SortedSet iteration ordering
      super('b', 'a', 'c', 'd', 'e');
    }
  }

  public static class Enums extends SampleElements<AnEnum> {
    public Enums() {
      // elements aren't sorted, to better test SortedSet iteration ordering
      super(AnEnum.B, AnEnum.A, AnEnum.C, AnEnum.D, AnEnum.E);
    }
  }

  @CheckForNull
  public V put(K key, @ParametricNullness V value) {
    return super.put(key, value);
  }

  @CanIgnoreReturnValue
  @Override
  @SuppressWarnings("RedundantOverride") // b/192446478: RedundantOverride ignores some annotations.
  // TODO(b/192446998): Remove this override after tools understand nullness better.
  @CheckForNull

 *
 * <p>The {@link #count} and {@link #size} implementations all iterate across the set returned by
 * {@link Multiset#entrySet()}, as do many methods acting on the set returned by {@link
 * #elementSet()}. Override those methods for better performance.
 *
 * @author Louis Wasserman
 */
@GwtCompatible(emulated = true)
@ElementTypesAreNonnullByDefault
abstract class AbstractSortedMultiset<E extends @Nullable Object> extends AbstractMultiset<E>

        .putShort((short) 0x0000)
        .putShort((short) 0x0000);
    assertEquals(hashCode, hasher.hash().asLong());
  }

  public void testHashFloatIsStable() {
    // Just a spot check.  Better than nothing.
    Hasher hasher = HASH_FN.newHasher();
    hasher.putFloat(0x01000101f).putFloat(0f);
    assertEquals(0x49f9d18ee8ae1b28L, hasher.hash().asLong());

    hasher = HASH_FN.newHasher();

  private String leave() {
    return "leave";
  }

  public final void testMutualExclusion() throws Exception {
    thread1.callAndAssertReturns(enter());
    thread2.callAndAssertBlocks(enter());
    thread1.callAndAssertReturns(leave());
    thread2.assertPriorCallReturns(enter());
  }

  public final void testTryEnter() throws Exception {
    thread1.callAndAssertReturns(true, tryEnter());

    return method.getAnnotation(AllowConcurrentEvents.class) != null;
  }

  /**
   * Subscriber that synchronizes invocations of a method to ensure that only one thread may enter
   * the method at a time.
   */
  @VisibleForTesting
  static final class SynchronizedSubscriber extends Subscriber {

    private SynchronizedSubscriber(EventBus bus, Object target, Method method) {

    linkedHashMultiset = LinkedHashMultiset.create(size);
    treeMultiset = TreeMultiset.create();

    Random random = new Random();

    int sizeRemaining = size;

    // TODO(kevinb): generate better test contents for multisets
    for (int i = 0; sizeRemaining > 0; i++) {
      // The JVM will return interned values for small ints.
      Integer value = random.nextInt(1000) + 128;