* <p>To implement a multimap, a subclass must define the method {@link #createCollection()}, which
 * creates an empty collection of values for a key.
 *
 * <p>The multimap constructor takes a map that has a single entry for each distinct key. When you
 * insert a key-value pair with a key that isn't already in the multimap, {@code
 * AbstractMapBasedMultimap} calls {@link #createCollection()} to create the collection of values

            : DEFAULT_VALUES_PER_KEY);
    putAll(multimap);
  }

  /**
   * Creates a new, empty {@code ArrayList} to hold the collection of values for an arbitrary key.
   */
  @Override
  List<V> createCollection() {
    return new ArrayList<>(expectedValuesPerKey);
  }

  /**
   * Reduces the memory used by this {@code ArrayListMultimap}, if feasible.
   *