return backingMap.get(element);
  }

  // Optional Operations - Modification Operations

  /**
   * {@inheritDoc}
   *
   * @throws IllegalArgumentException if the call would result in more than {@link
   *     Integer#MAX_VALUE} occurrences of {@code element} in this multiset.
   */
  @CanIgnoreReturnValue
  @Override
  public final int add(@ParametricNullness E element, int occurrences) {

    return new MapBasedMultisetIterator();
  }

  /*
   * Not subclassing AbstractMultiset$MultisetIterator because next() needs to
   * retrieve the Map.Entry<E, Count> entry, which can then be used for
   * a more efficient remove() call.
   */
  private class MapBasedMultisetIterator implements Iterator<E> {
    final Iterator<Map.Entry<E, Count>> entryIterator;
    @CheckForNull Map.Entry<E, Count> currentEntry;