* not present). When the collection delegate in the WrappedCollection is
   * empty, the multimap may contain subsequently added values for that key. To
   * handle that situation, the WrappedCollection checks whether map contains
   * an entry for the provided key, and if so replaces the delegate.
   */

  private transient Map<K, Collection<V>> map;

   * not present). When the collection delegate in the WrappedCollection is
   * empty, the multimap may contain subsequently added values for that key. To
   * handle that situation, the WrappedCollection checks whether map contains
   * an entry for the provided key, and if so replaces the delegate.
   */

  private transient Map<K, Collection<V>> map;