import org.jspecify.annotations.Nullable;

/**
 * A simplistic set which implements the bare minimum so that it can be used in tests without
 * relying on any specific Set implementations. Slow. Explicitly allows null elements so that they
 * can be used in the testers.
 *
 * @author Regina O'Dell
 */
@GwtCompatible
@NullMarked
public class MinimalSet<E extends @Nullable Object> extends MinimalCollection<E> implements Set<E> {

     */
    public InvokerException(@Nullable String message) {
        super(message);
    }

    /**
     * Constructs a new {@code InvokerException} with the specified detail message and cause.
     *
     * @param message the detail message explaining the cause of the exception
     * @param cause the underlying cause of the exception
     */
    public InvokerException(@Nullable String message, @Nullable Throwable cause) {

   *
   * @since 21.0 (but only since 33.4.0 in the Android flavor)
   */
  @SuppressWarnings("NullableOptional") // Null passthrough is reasonable for type conversions
  public static <T> @Nullable Optional<T> fromJavaUtil(
      java.util.@Nullable Optional<T> javaUtilOptional) {
    return (javaUtilOptional == null) ? null : fromNullable(javaUtilOptional.orElse(null));
  }

  /**

   */
  @Override
  public boolean containsValue(@Nullable Object value) {
    return findEntryByValue(value) != ABSENT;
  }

  @Override
  public @Nullable V get(@Nullable Object key) {
    int entry = findEntryByKey(key);
    return (entry == ABSENT) ? null : values[entry];
  }

  @Nullable K getInverse(@Nullable Object value) {
    int entry = findEntryByValue(value);

 * @author Louis Wasserman
 */
@GwtCompatible
abstract class AbstractMultiset<E extends @Nullable Object> extends AbstractCollection<E>
    implements Multiset<E> {
  // Query Operations

  @Override
  public boolean isEmpty() {
    return entrySet().isEmpty();
  }

  @Override
  public boolean contains(@Nullable Object element) {
    return count(element) > 0;
  }

  // Modification Operations

import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
import org.jspecify.annotations.Nullable;

/**
 * A skeleton {@code Multimap} implementation, not necessarily in terms of a {@code Map}.
 *
 * @author Louis Wasserman
 */
@GwtCompatible
abstract class AbstractMultimap<K extends @Nullable Object, V extends @Nullable Object>
    implements Multimap<K, V> {
  @Override
  public boolean isEmpty() {

    return result;
  }

  @Override
  public @Nullable Entry<E> firstEntry() {
    return delegate().firstEntry();
  }

  @Override
  public @Nullable Entry<E> lastEntry() {
    return delegate().lastEntry();
  }

  @Override
  public @Nullable Entry<E> pollFirstEntry() {
    throw new UnsupportedOperationException();
  }

  @Override
  public @Nullable Entry<E> pollLastEntry() {

abstract class AbstractAbstractFutureTest extends TestCase {
  @SuppressWarnings("initialization.field.uninitialized")
  private TestedFuture<@Nullable Integer> future;

  @SuppressWarnings("initialization.field.uninitialized")
  private AbstractFuture<@Nullable Integer> delegate;

  abstract AbstractFuture<@Nullable Integer> newDelegate();

  @Override
  protected void setUp() {
    future = TestedFuture.create();
    delegate = newDelegate();
  }

      assertTrue(Thread.holdsLock(mutex));
      return delegate.containsRow(rowKey);
    }

    @Override
    public @Nullable V get(Object rowKey, Object columnKey) {
      assertTrue(Thread.holdsLock(mutex));
      return delegate.get(rowKey, columnKey);
    }

    @Override
    public @Nullable V put(R rowKey, C columnKey, V value) {
      assertTrue(Thread.holdsLock(mutex));

    static final Listener TOMBSTONE = new Listener();
    // null only for TOMBSTONE
    final @Nullable Runnable task;
    // null only for TOMBSTONE
    final @Nullable Executor executor;

    // writes to next are made visible by subsequent CAS's on the listeners field
    @Nullable Listener next;

    Listener(Runnable task, Executor executor) {
      this.task = task;
      this.executor = executor;