abstract <R> @Nullable R dummyReturnValue(TypeToken<R> returnType);

  private final class DummyHandler extends AbstractInvocationHandler implements Serializable {
    private final TypeToken<?> interfaceType;

    DummyHandler(TypeToken<?> interfaceType) {
      this.interfaceType = interfaceType;
    }

    @Override
    protected @Nullable Object handleInvocation(

     */
    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) {

  public abstract UnmodifiableIterator<E> iterator();

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

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

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

  @Override

   * equal to any other equality groups added to this tester.
   *
   * <p>The {@code @Nullable} annotations on the {@code equalityGroup} parameter imply that the
   * objects, and the array itself, can be null. That is for programmer convenience, when the
   * objects come from factory methods that are themselves {@code @Nullable}. In reality neither the
   * array nor its contents can be null, but it is not useful to force the use of {@code

import org.apache.maven.api.annotations.Immutable;
import org.apache.maven.api.annotations.Nonnull;
import org.apache.maven.api.annotations.NotThreadSafe;
import org.apache.maven.api.annotations.Nullable;

import static java.util.Objects.requireNonNull;

/**
 * A request for installing one or more artifacts in the local repository.
 *
 * @since 4.0.0
 */
@Experimental
@Immutable

// @Ignore affects the Android test runner, which respects JUnit 4 annotations on JUnit 3 tests.
@SuppressWarnings("JUnit4ClassUsedInJUnit3")
@NullMarked
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() {

import java.util.List;
import org.jspecify.annotations.NullMarked;
import org.jspecify.annotations.Nullable;

/**
 * Creates sets, containing sample elements, to be tested.
 *
 * @author Kevin Bourrillion
 */
@GwtCompatible
@NullMarked
public interface TestListGenerator<E extends @Nullable Object> extends TestCollectionGenerator<E> {
  @Override
  List<E> create(Object... elements);

import java.util.concurrent.ExecutionException;
import java.util.concurrent.Future;
import org.jspecify.annotations.Nullable;

/** Emulation of Uninterruptibles in GWT. */
public final class Uninterruptibles {

  private Uninterruptibles() {}

  @CanIgnoreReturnValue
  public static <V extends @Nullable Object> V getUninterruptibly(Future<V> future)
      throws ExecutionException {
    try {
      return future.get();

// @Ignore affects the Android test runner, which respects JUnit 4 annotations on JUnit 3 tests.
@SuppressWarnings("JUnit4ClassUsedInJUnit3")
@NullMarked
public class MultimapSizeTester<K extends @Nullable Object, V extends @Nullable Object>
    extends AbstractMultimapTester<K, V, Multimap<K, V>> {

  public void testSize() {
    int expectedSize = getNumElements();
    Multimap<K, V> multimap = multimap();

import static java.util.Collections.singletonMap;

import org.jspecify.annotations.Nullable;

/**
 * GWT emulation of {@link SingletonImmutableBiMap}.
 *
 * @author Hayward Chan
 */
final class SingletonImmutableBiMap<K, V> extends ImmutableBiMap<K, V> {
  private final K singleKey;
  private final V singleValue;

  @Nullable transient SingletonImmutableBiMap<V, K> inverse;

  SingletonImmutableBiMap(K key, V value) {