public abstract UnmodifiableIterator<E> iterator();

  public boolean contains(@Nullable Object object) {
    return object != null && super.contains(object);
  }

  public final boolean add(E e) {
    throw new UnsupportedOperationException();
  }

  public final boolean remove(@Nullable Object object) {
    throw new UnsupportedOperationException();
  }

    public boolean containsKey(@Nullable Object key) {
      assertTrue(Thread.holdsLock(mutex));
      return super.containsKey(key);
    }

    @Override
    public boolean containsValue(@Nullable Object value) {
      assertTrue(Thread.holdsLock(mutex));
      return super.containsValue(value);
    }

    @Override
    public boolean containsEntry(@Nullable Object key, @Nullable Object value) {

  public final Set<Feature<?>> getAbsentFeatures() {
    return absentFeatures;
  }

  @Override
  public boolean equals(@Nullable Object object) {
    if (object == this) {
      return true;
    }
    if (object instanceof TesterRequirements) {
      TesterRequirements that = (TesterRequirements) object;
      return this.presentFeatures.equals(that.presentFeatures)
          && this.absentFeatures.equals(that.absentFeatures);
    }

    return Optional.absent();
  }

  @Override
  public boolean equals(@CheckForNull Object object) {
    return object == this;
  }

  @Override
  public int hashCode() {
    return 0x79a31aac;
  }

  @Override
  public String toString() {
    return "Optional.absent()";
  }

  private Object readResolve() {
    return INSTANCE;
  }

  private static final long serialVersionUID = 0;

    return Optional.absent();
  }

  @Override
  public boolean equals(@CheckForNull Object object) {
    return object == this;
  }

  @Override
  public int hashCode() {
    return 0x79a31aac;
  }

  @Override
  public String toString() {
    return "Optional.absent()";
  }

  private Object readResolve() {
    return INSTANCE;
  }

  private static final long serialVersionUID = 0;

 *
 * @author Mike Bostock
 */
public class ForwardingObjectTest extends TestCase {

  public void testEqualsReflexive() {
    final Object delegate = new Object();
    ForwardingObject forward =
        new ForwardingObject() {
          @Override
          protected Object delegate() {
            return delegate;
          }
        };
    new EqualsTester().addEqualityGroup(forward).testEquals();
  }

   */
  boolean apply(@ParametricNullness T input);

  /**
   * Indicates whether another object is equal to this predicate.
   *
   * <p>Most implementations will have no reason to override the behavior of {@link Object#equals}.
   * However, an implementation may also choose to return {@code true} whenever {@code object} is a
   * {@link Predicate} that it considers <i>interchangeable</i> with this one. "Interchangeable"

 * consumption at the price of moderately increased constant factors of CPU. Only use this class
 * when there is a specific reason to prioritize memory over CPU.
 *
 * @author Louis Wasserman
 */
@GwtIncompatible // not worth using in GWT for now
@ElementTypesAreNonnullByDefault
class CompactLinkedHashSet<E extends @Nullable Object> extends CompactHashSet<E> {

   * result from the user invoking {@link Cache#put}, {@link LoadingCache#refresh}, {@link Map#put},
   * {@link Map#putAll}, {@link ConcurrentMap#replace(Object, Object)}, or {@link
   * ConcurrentMap#replace(Object, Object, Object)}.
   */
  REPLACED {
    @Override
    boolean wasEvicted() {
      return false;
    }
  },

  /**

 */
@GwtCompatible
@Ignore // Affects only Android test runner, which respects JUnit 4 annotations on JUnit 3 tests.
@ElementTypesAreNonnullByDefault
public abstract class AbstractMapTester<K extends @Nullable Object, V extends @Nullable Object>
    extends AbstractContainerTester<Map<K, V>, Entry<K, V>> {
  protected Map<K, V> getMap() {
    return container;
  }

  @Override
  protected Collection<Entry<K, V>> actualContents() {