assertEquals(expectedMean, IntMath.mean(x, y));
    assertEquals(
        "The mean of x and y should equal the mean of y and x", expectedMean, IntMath.mean(y, x));
  }

  /**
   * Computes the mean in a way that is obvious and resilient to overflow by using BigInteger
   * arithmetic.
   */
  private static int computeMeanSafely(int x, int y) {
    BigInteger bigX = BigInteger.valueOf(x);

    for (Service service : copy) {
      service.addListener(new ServiceListener(service, stateReference), directExecutor());
      // We check the state after adding the listener as a way to ensure that our listener was added
      // to a NEW service.
      checkArgument(service.state() == NEW, "Can only manage NEW services, %s", service);
    }

    for (Service service : copy) {
      service.addListener(new ServiceListener(service, stateReference), directExecutor());
      // We check the state after adding the listener as a way to ensure that our listener was added
      // to a NEW service.
      checkArgument(service.state() == NEW, "Can only manage NEW services, %s", service);
    }

 * "the same," <i>unless specified otherwise</i> by the implementation.
 *
 * <p><b>Warning:</b> as with normal {@link Set}s, it is almost always a bad idea to modify an
 * element (in a way that affects its {@link Object#equals} behavior) while it is contained in a
 * multiset. Undefined behavior and bugs will result.
 *
 * <h3>Implementations</h3>
 *
 * <ul>
 *   <li>{@link ImmutableMultiset}

   * Maximum allowed length of a hash table bucket before falling back to a j.u.LinkedHashMap-based
   * implementation. Experimentally determined.
   */
  private static final int MAX_HASH_BUCKET_LENGTH = 9;

  // The way the `table`, `entries`, `keys`, and `values` arrays work together is as follows.
  //
  // The `table` array always has a size that is a power of 2. The hashcode of a key in the map

 *
 * <p>The following types of methods are provided:
 *
 * <ul>
 *   <li>chaining methods which return a new {@code FluentIterable} based in some way on the
 *       contents of the current one (for example {@link #transform})
 *   <li>element extraction methods which facilitate the retrieval of certain elements (for example
 *       {@link #last})

 *       {@code fail}, {@code assertTrue}, etc.) It is OK (but not particularly recommended) for
 *       other code to use these forms too. Only the most typically used JUnit assertion methods are
 *       defined this way, but enough to live with.
 *   <li>If you override {@link #setUp} or {@link #tearDown}, make sure to invoke {@code
 *       super.setUp} and {@code super.tearDown} within them. These methods are used to clear and

 * "the same," <i>unless specified otherwise</i> by the implementation.
 *
 * <p><b>Warning:</b> as with normal {@link Set}s, it is almost always a bad idea to modify an
 * element (in a way that affects its {@link Object#equals} behavior) while it is contained in a
 * multiset. Undefined behavior and bugs will result.
 *
 * <h3>Implementations</h3>
 *
 * <ul>
 *   <li>{@link ImmutableMultiset}

   * list is a transformed view of {@code fromList}; changes to {@code fromList} will be reflected
   * in the returned list and vice versa.
   *
   * <p>Since functions are not reversible, the transform is one-way and new items cannot be stored
   * in the returned list. The {@code add}, {@code addAll} and {@code set} methods are unsupported
   * in the returned list.
   *

  }

  /*
   * TODO(kevinb): should we copy this javadoc to each concrete class, so that
   * classes like LinkedHashMultimap that need to say something different are
   * still able to {@inheritDoc} all the way from Multimap?
   */

  @Override
  Multiset<K> createKeys() {
    return new Multimaps.Keys<K, V>(this);
  }

  /**
   * {@inheritDoc}
   *