assertEquals(getMultiset().entrySet().hashCode(), getMultiset().hashCode());
  }

  @CollectionSize.Require(absent = ZERO)
  @CollectionFeature.Require(ALLOWS_NULL_VALUES)
  public void testEqualsMultisetWithNullValue() {
    new EqualsTester()
        .addEqualityGroup(getMultiset())
        .addEqualityGroup(
            getSubjectGenerator().create(createArrayWithNullElement()),

        collection.containsAll(MinimalCollection.of(e3())));
  }

  @CollectionFeature.Require(absent = ALLOWS_NULL_QUERIES)
  public void testContainsAll_nullNotAllowed() {
    try {
      assertFalse(collection.containsAll(MinimalCollection.of((E) null)));
    } catch (NullPointerException tolerated) {
    }
  }

  @CollectionFeature.Require(ALLOWS_NULL_QUERIES)
  public void testContainsAll_nullAllowed() {

  }

  @CollectionSize.Require(absent = CollectionSize.ZERO)
  public void testEquals_otherListContainingNull() {
    List<E> other = new ArrayList<>(getSampleElements());
    other.set(other.size() / 2, null);
    assertFalse(
        "Two Lists should not be equal if exactly one of them has null at a given index.",
        getList().equals(other));
  }

  @CollectionSize.Require(absent = CollectionSize.ZERO)

      TypeVariable<?>[] typeVars = rawType.getTypeParameters();
      for (int i = 0; i < params.size(); i++) {
        TypeToken<?> paramType = type.resolveType(typeVars[i]);
        // We require all @Generates methods to either be parameter-less or accept non-null
        // values for their generic parameter types.
        Object argValue = generate(paramType);
        if (argValue == null) {

 * supertype of `Function<A, B>` turns out to be massively more useful to callers in practice: They
 * want their output to be non-null in operations like `stream.map(myConverter)`, and we can
 * guarantee that as long as we also require the input type to be non-null[*] (which is a
 * requirement that existing callers already fulfill).
 *
 * Disclaimer: Part of the reason that callers are so well adapted to `Function<A, B>` may be that

   * reconstructed using public factory methods. This ensures that the implementation types remain
   * as implementation details.
   *
   * <p>Since the bimap is immutable, ImmutableBiMap doesn't require special logic for keeping the
   * bimap and its inverse in sync during serialization, the way AbstractBiMap does.
   */
  @J2ktIncompatible // serialization

@SuppressWarnings("JUnit4ClassUsedInJUnit3")
public class QueueElementTester<E> extends AbstractQueueTester<E> {
  @CollectionSize.Require(ZERO)
  public void testElement_empty() {
    assertThrows(NoSuchElementException.class, () -> getQueue().element());
    expectUnchanged();
  }

  @CollectionSize.Require(ONE)
  public void testElement_size1() {
    assertEquals("size1Queue.element() should return first element", e0(), getQueue().element());

@SuppressWarnings("JUnit4ClassUsedInJUnit3")
public class QueuePeekTester<E> extends AbstractQueueTester<E> {
  @CollectionSize.Require(ZERO)
  public void testPeek_empty() {
    assertNull("emptyQueue.peek() should return null", getQueue().peek());
    expectUnchanged();
  }

  @CollectionSize.Require(ONE)
  public void testPeek_size1() {
    assertEquals("size1Queue.peek() should return first element", e0(), getQueue().peek());

@SuppressWarnings("JUnit4ClassUsedInJUnit3")
public class QueueOfferTester<E> extends AbstractQueueTester<E> {
  @CollectionFeature.Require(SUPPORTS_ADD)
  public void testOffer_supportedNotPresent() {
    assertTrue("offer(notPresent) should return true", getQueue().offer(e3()));
    expectAdded(e3());
  }

  @CollectionFeature.Require({SUPPORTS_ADD, ALLOWS_NULL_VALUES})
  public void testOffer_nullSupported() {

  @CollectionFeature.Require(absent = SUPPORTS_REMOVE)
  @ListFeature.Require(absent = {SUPPORTS_SET, SUPPORTS_ADD_WITH_INDEX})
  public void testListIterator_unmodifiable() {
    runListIteratorTest(UNMODIFIABLE);
  }

  /*
   * For now, we don't cope with testing this when the list supports only some
   * modification operations.
   */
  @CollectionFeature.Require(SUPPORTS_REMOVE)