*
   * @return the collection of replaced values, or an empty collection if no values were previously
   *     associated with the key. The collection <i>may</i> be modifiable, but updating it will have
   *     no effect on the multimap.
   */
  @CanIgnoreReturnValue
  Collection<V> replaceValues(@ParametricNullness K key, Iterable<? extends V> values);

  /**