// used under GWT, etc., since the override of this method does not exist there
    ImmutableMap<Class<? extends Throwable>, Predicate<Throwable>> exceptions() {
      return ImmutableMap.of();
    }
  }

  private static final ImmutableMap<Class<? extends Throwable>, Predicate<Throwable>> INSTANCE_OF =
      ImmutableMap.<Class<? extends Throwable>, Predicate<Throwable>>builder()

      Runnable task, @ParametricNullness T result) {
    return (ListenableFuture<T>) super.submit(task, result);
  }

  @CanIgnoreReturnValue // TODO(kak): consider removing this
  @Override
  public <T extends @Nullable Object> ListenableFuture<T> submit(Callable<T> task) {
    return (ListenableFuture<T>) super.submit(task);
  }

import org.jspecify.annotations.NonNull;
import org.jspecify.annotations.Nullable;

/** An ordering that treats {@code null} as less than all other values. */
@GwtCompatible
final class NullsFirstOrdering<T extends @Nullable Object> extends Ordering<@Nullable T>
    implements Serializable {
  final Ordering<? super T> ordering;

  NullsFirstOrdering(Ordering<? super T> ordering) {
    this.ordering = ordering;
  }

  @Override

 * @author Kevin Bourrillion
 * @author Jared Levy
 * @since 2.0
 */
@GwtCompatible
public final class LinkedHashMultiset<E extends @Nullable Object>
    extends AbstractMapBasedMultiset<E> {

  /** Creates a new, empty {@code LinkedHashMultiset} using the default initial capacity. */
  public static <E extends @Nullable Object> LinkedHashMultiset<E> create() {
    return new LinkedHashMultiset<>();
  }

  /**

    public String toString() {
      return "another arbitrary string";
    }
  }

  private static class SubHandler1 extends DelegatingInvocationHandlerWithEquals {
    SubHandler1(Object delegate) {
      super(delegate);
    }
  }

  private static class SubHandler2 extends DelegatingInvocationHandlerWithEquals {
    SubHandler2(Object delegate) {
      super(delegate);
    }
  }

 * #elementSet()}. Override those methods for better performance.
 *
 * @author Kevin Bourrillion
 * @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

 * #createCollection} method must return a {@code Set}.
 *
 * @author Jared Levy
 */
@GwtCompatible
abstract class AbstractSetMultimap<K extends @Nullable Object, V extends @Nullable Object>
    extends AbstractMapBasedMultimap<K, V> implements SetMultimap<K, V> {
  /**
   * Creates a new multimap that uses the provided map.
   *

    return new CacheLoader<K, V>() {
      @Override
      public V load(K key) throws Exception {
        return loader.load(key);
      }

      @Override
      public Map<K, V> loadAll(Iterable<? extends K> keys) throws Exception {
        Map<K, V> result = new HashMap<>(); // allow nulls
        for (K key : keys) {
          result.put(key, load(key));
        }
        return result;
      }
    };
  }

 * #createCollection} method must return a {@code Set}.
 *
 * @author Jared Levy
 */
@GwtCompatible
abstract class AbstractSetMultimap<K extends @Nullable Object, V extends @Nullable Object>
    extends AbstractMapBasedMultimap<K, V> implements SetMultimap<K, V> {
  /**
   * Creates a new multimap that uses the provided map.
   *

 * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#bimap">{@code BiMap}</a>.
 *
 * @author Kevin Bourrillion
 * @since 2.0
 */
@GwtCompatible
public interface BiMap<K extends @Nullable Object, V extends @Nullable Object> extends Map<K, V> {
  // Modification Operations

  /**
   * {@inheritDoc}
   *
   * @throws IllegalArgumentException if the given value is already bound to a different key in this