/**
 * Creates collections containing unhashable sample elements, to be tested.
 *
 * @author Regina O'Dell
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault
public abstract class TestUnhashableCollectionGenerator<T extends Collection<UnhashableObject>>
    implements TestCollectionGenerator<UnhashableObject> {
  @Override
  public SampleElements<UnhashableObject> samples() {
    return new Unhashables();
  }

  @Override

/**
 * Creates collections containing unhashable sample elements, to be tested.
 *
 * @author Regina O'Dell
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault
public abstract class TestUnhashableCollectionGenerator<T extends Collection<UnhashableObject>>
    implements TestCollectionGenerator<UnhashableObject> {
  @Override
  public SampleElements<UnhashableObject> samples() {
    return new Unhashables();
  }

  @Override

 * @author George van den Driessche
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault
public interface TestContainerGenerator<T, E extends @Nullable Object> {
  /** Returns the sample elements that this generate populates its container with. */
  SampleElements<E> samples();

  /**
   * Creates a new container containing the given elements. TODO: would be nice to figure out how to

![Events Diagram](../assets/images/******@****.***)

Here’s a [sample event listener](https://github.com/square/okhttp/blob/master/samples/guide/src/main/java/okhttp3/recipes/PrintEventsNonConcurrent.java) that prints each event with a timestamp.

```java
class PrintingEventListener extends EventListener {

 * @author George van den Driessche
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault
public interface TestContainerGenerator<T, E extends @Nullable Object> {
  /** Returns the sample elements that this generate populates its container with. */
  SampleElements<E> samples();

  /**
   * Creates a new container containing the given elements. TODO: would be nice to figure out how to

            ImmutableSet.of(1, 2),
            ImmutableSet.of(1, 2, 3, 4, 5, 6, 7, 8, 9, 10));
    for (Set<Integer> sampleSet : sampleSets) {
      for (int k = 0; k <= sampleSet.size(); k++) {
        final int size = k;
        Set<Set<Integer>> expected =
            Sets.filter(
                Sets.powerSet(sampleSet),
                new Predicate<Set<Integer>>() {

                  @Override

    }

    @Override
    public SampleElements<Entry<V, K>> samples() {
      SampleElements<Entry<K, V>> samples = generator.samples();
      return new SampleElements<>(
          reverse(samples.e0()),
          reverse(samples.e1()),
          reverse(samples.e2()),
          reverse(samples.e3()),
          reverse(samples.e4()));
    }

    private Entry<V, K> reverse(Entry<K, V> entry) {

    return generator.create(elements.toArray());
  }

  @Override
  public Collection<E> getSampleElements(int howMany) {
    SampleElements<E> samples = samples();
    List<E> allSampleElements =
        asList(samples.e0(), samples.e1(), samples.e2(), samples.e3(), samples.e4());
    return new ArrayList<>(allSampleElements.subList(0, howMany));
  }

  @Override
  public CollectionSize getCollectionSize() {

    getList().replaceAll(e -> samples.e3());
    expectContents(nCopies(getNumElements(), samples.e3()));
  }

  @ListFeature.Require(SUPPORTS_SET)
  public void testReplaceAll_changesSome() {
    getList().replaceAll(e -> e.equals(samples.e0()) ? samples.e3() : e);
    E[] expected = createSamplesArray();
    for (int i = 0; i < expected.length; i++) {
      if (expected[i].equals(samples.e0())) {
        expected[i] = samples.e3();

    }

    @Override
    public SampleElements<Entry<V, K>> samples() {
      SampleElements<Entry<K, V>> samples = generator.samples();
      return new SampleElements<>(
          reverse(samples.e0()),
          reverse(samples.e1()),
          reverse(samples.e2()),
          reverse(samples.e3()),
          reverse(samples.e4()));
    }

    private Entry<V, K> reverse(Entry<K, V> entry) {