* Multiset}.
   */
  @CanIgnoreReturnValue
  @Override
  public final boolean addAll(Collection<? extends E> elementsToAdd) {
    return Multisets.addAllImpl(this, elementsToAdd);
  }

  @CanIgnoreReturnValue
  @Override
  public final boolean removeAll(Collection<?> elementsToRemove) {
    return Multisets.removeAllImpl(this, elementsToRemove);
  }