}

  @Override
  public boolean containsValue(@CheckForNull Object value) {
    return values().contains(value);
  }

  // Modification Operations

  /**
   * Stores a key-value pair in the multimap.
   *
   * @param key key to store in the multimap
   * @param value value to store in the multimap
   * @return {@code true} always
   */
  @CanIgnoreReturnValue
  @Override

   * iterable supports it. Note that it is <i>not</i> possible to delete the last skipped element by
   * immediately calling {@code remove()} on that iterator, as the {@code Iterator} contract states
   * that a call to {@code remove()} before a call to {@code next()} will throw an {@link
   * IllegalStateException}.
   *
   * <p><b>{@code Stream} equivalent:</b> {@link Stream#skip}
   *
   * @since 3.0

 * therefore every method of the listener will be called at most once. N.B. The {@link State#FAILED}
 * and {@link State#TERMINATED} states are terminal states, once a service enters either of these
 * states it cannot ever leave them.
 *
 * <p>Implementors of this interface are strongly encouraged to extend one of the abstract classes

    }
  }

  /**
   * This method returns a {@code ImmutableSortedMap}, consisting of the entries whose keys are less
   * than {@code toKey}.
   *
   * <p>The {@link SortedMap#headMap} documentation states that a submap of a submap throws an
   * {@link IllegalArgumentException} if passed a {@code toKey} greater than an earlier {@code
   * toKey}. However, this method doesn't throw an exception in that situation, but instead keeps

   * documentation.
   */
  public void add(Runnable runnable, Executor executor) {
    // Fail fast on a null. We throw NPE here because the contract of Executor states that it throws
    // NPE on null listener, so we propagate that contract up into the add method as well.
    checkNotNull(runnable, "Runnable was null.");
    checkNotNull(executor, "Executor was null.");

 *       differ significantly. And sometimes testcases cover multiple methods when they cannot be
 *       tested in isolation.
 *   <li>The documentation style for testcases is to provide as javadoc a simple sentence or two
 *       describing the property that the testcase method purports to test. The javadocs do not say

      for (Entry<? extends K, ? extends V> entry : entries) {
        put(entry);
      }
      return this;
    }

    /**
     * Stores a collection of values with the same key in the built multimap.
     *
     * @throws NullPointerException if {@code key}, {@code values}, or any element in {@code values}

      for (Entry<? extends K, ? extends V> entry : entries) {
        put(entry);
      }
      return this;
    }

    /**
     * Stores a collection of values with the same key in the built multimap.
     *
     * @throws NullPointerException if {@code key}, {@code values}, or any element in {@code values}

 *
 * <p>This implementation is based on the <a
 * href="http://portal.acm.org/citation.cfm?id=6621">min-max heap</a> developed by Atkinson, et al.
 * Unlike many other double-ended priority queues, it stores elements in a single array, as compact
 * as the traditional heap data structure used in {@link PriorityQueue}.
 *
 * <p>This class is not thread-safe, and does not accept null elements.
 *
 * <p><i>Performance notes:</i>

// Since this class only needs CAS on one field, we can avoid this bug by extending AtomicReference
// instead of using an AtomicReferenceFieldUpdater. This reference stores Thread instances
// and DONE/INTERRUPTED - they have a common ancestor of Runnable.
abstract class InterruptibleTask<T extends @Nullable Object>
    extends AtomicReference<@Nullable Runnable> implements Runnable {
  static {