@SuppressWarnings("JUnit4ClassUsedInJUnit3")
public class ListCreationTester<E> extends AbstractListTester<E> {
  @CollectionFeature.Require(absent = REJECTS_DUPLICATES_AT_CREATION)
  @CollectionSize.Require(absent = {ZERO, ONE})
  public void testCreateWithDuplicates() {
    E[] array = createSamplesArray();
    array[1] = e0();
    collection = getSubjectGenerator().create(array);

Pydantic has a special behavior when you use `Optional` or `Union[Something, None]` without a default value, you can read more about it in the Pydantic docs about <a href="https://docs.pydantic.dev/2.3/usage/models/#required-fields" class="external-link" target="_blank">Required Optional fields</a>.

///

## Type Hints with Metadata Annotations { #type-hints-with-metadata-annotations }

  @ListFeature.Require(SUPPORTS_REMOVE_WITH_INDEX)
  @CollectionSize.Require(absent = {ZERO, ONE})
  public void testRemoveAtIndex_middle() {
    runRemoveTest(getNumElements() / 2);
  }

  @CollectionFeature.Require(FAILS_FAST_ON_CONCURRENT_MODIFICATION)
  @ListFeature.Require(SUPPORTS_REMOVE_WITH_INDEX)
  @CollectionSize.Require(absent = ZERO)
  public void testRemoveAtIndexConcurrentWithIteration() {
    assertThrows(

@SuppressWarnings("JUnit4ClassUsedInJUnit3")
public class ListCreationTester<E> extends AbstractListTester<E> {
  @CollectionFeature.Require(absent = REJECTS_DUPLICATES_AT_CREATION)
  @CollectionSize.Require(absent = {ZERO, ONE})
  public void testCreateWithDuplicates() {
    E[] array = createSamplesArray();
    array[1] = e0();
    collection = getSubjectGenerator().create(array);

@SuppressWarnings("JUnit4ClassUsedInJUnit3")
public class MultisetAddTester<E> extends AbstractMultisetTester<E> {
  @CollectionFeature.Require(absent = SUPPORTS_ADD)
  public void testAddUnsupported() {
    assertThrows(UnsupportedOperationException.class, () -> getMultiset().add(e0()));
  }

  @CollectionFeature.Require(SUPPORTS_ADD)
  public void testAddMeansAddOne() {
    int originalCount = getMultiset().count(e0());

  }

  @CollectionFeature.Require(SUPPORTS_ITERATOR_REMOVE)
  @CollectionSize.Require(absent = ZERO)
  public void testRemoveIf_allPresent() {
    assertTrue("removeIf(x -> true) should return true", collection.removeIf(x -> true));
    expectContents();
  }

  @CollectionFeature.Require({SUPPORTS_ITERATOR_REMOVE, FAILS_FAST_ON_CONCURRENT_MODIFICATION})
  @CollectionSize.Require(SEVERAL)

    return (ConcurrentMap<K, V>) super.getMap();
  }

  @MapFeature.Require(SUPPORTS_PUT)
  @CollectionSize.Require(absent = ZERO)
  public void testReplace_supportedPresent() {
    assertEquals(v0(), getMap().replace(k0(), v3()));
    expectReplacement(entry(k0(), v3()));
  }

  @MapFeature.Require(SUPPORTS_PUT)
  @CollectionSize.Require(absent = ZERO)
  public void testReplace_supportedPresentNoChange() {

  @MapFeature.Require(SUPPORTS_PUT)
  @CollectionSize.Require(absent = ZERO)
  public void testReplace_supportedPresent() {
    try {
      assertEquals(v0(), getMap().replace(k0(), v3()));
      expectReplacement(entry(k0(), v3()));
    } catch (ClassCastException tolerated) { // for ClassToInstanceMap
      expectUnchanged();
    }
  }

  @MapFeature.Require(SUPPORTS_PUT)

@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() {

public class BiMapClearTester<K, V> extends AbstractBiMapTester<K, V> {
  @MapFeature.Require(SUPPORTS_REMOVE)
  public void testClearClearsInverse() {
    BiMap<V, K> inv = getMap().inverse();
    getMap().clear();
    assertTrue(getMap().isEmpty());
    assertTrue(inv.isEmpty());
  }

  @MapFeature.Require(SUPPORTS_REMOVE)
  public void testKeySetClearClearsInverse() {
    BiMap<V, K> inv = getMap().inverse();