* @since 11.0
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault
public interface AsyncFunction<I extends @Nullable Object, O extends @Nullable Object> {
  /**
   * Returns an output {@code Future} to use in place of the given {@code input}. The output {@code
   * Future} need not be {@linkplain Future#isDone done}, making {@code AsyncFunction} suitable for
   * asynchronous derivations.
   *

    int i = 0;
    for (Object e : elements) {
      array[i++] = (UnhashableObject) e;
    }
    return create(array);
  }

  /**
   * Creates a new collection containing the given elements; implement this method instead of {@link
   * #create(Object...)}.
   */
  protected abstract T create(UnhashableObject[] elements);

  @Override
  public UnhashableObject[] createArray(int length) {

    ImmutableSetMultimap.Builder<K, V> builder = ImmutableSetMultimap.builder();
    builder.put(k1, v1);
    return builder.build();
  }

  /**
   * Returns an immutable multimap containing the given entries, in order. Repeated occurrences of
   * an entry (according to {@link Object#equals}) after the first are ignored.
   */
  public static <K, V> ImmutableSetMultimap<K, V> of(K k1, V v1, K k2, V v2) {

    return ImmutableList.copyOf(elements);
  }

  /**
   * Utility method to verify that the given LinkedHashSet is equal to and hashes identically to a
   * set constructed with the elements in the given collection. Also verifies that the ordering in
   * the set is the same as the ordering of the given contents.
   */
  private static <E> void verifyLinkedHashSetContents(

 *
 * @since {@code com.google.guava:failureaccess:1.0}, which was added as a dependency of Guava in
 *     Guava 27.0
 */
public final class InternalFutures {
  /**
   * Usually returns {@code null} but, if the given {@code Future} has failed, may <i>optionally</i>
   * return the cause of the failure. "Failure" means specifically "completed with an exception"; it

import com.google.common.annotations.GwtCompatible;
import java.io.Serializable;
import java.util.List;
import javax.annotation.CheckForNull;

/** An ordering that compares objects according to a given order. */
@GwtCompatible(serializable = true)
@ElementTypesAreNonnullByDefault
final class ExplicitOrdering<T> extends Ordering<T> implements Serializable {
  final ImmutableMap<T, Integer> rankMap;

  @Override
  public String[] createArray(int length) {
    return new String[length];
  }

  /**
   * {@inheritDoc}
   *
   * <p>By default, returns the supplied elements in their given order; however, generators for
   * containers with a known order other than insertion order must override this method.
   *
   * <p>Note: This default implementation is overkill (but valid) for an unordered container. An

  @Override
  public Integer[] createArray(int length) {
    return new Integer[length];
  }

  /**
   * {@inheritDoc}
   *
   * <p>By default, returns the supplied elements in their given order; however, generators for
   * containers with a known order other than insertion order must override this method.
   *
   * <p>Note: This default implementation is overkill (but valid) for an unordered container. An

  /**
   * Waits for the {@link Service} to reach the {@linkplain State#RUNNING running state} for no more
   * than the given time.
   *
   * @param timeout the maximum time to wait
   * @param unit the time unit of the timeout argument
   * @throws TimeoutException if the service has not reached the given state within the deadline
   * @throws IllegalStateException if the service reaches a state from which it is not possible to

   * {@link Set}, instead of the {@link Collection} specified in the {@link Multimap} interface.
   */
  @Override
  public Set<V> get(@ParametricNullness K key) {
    return (Set<V>) super.get(key);
  }

  /**
   * {@inheritDoc}
   *
   * <p>Because a {@code SetMultimap} has unique values for a given key, this method returns a