checkNotNull(countFunction);
    return Collector.of(
        LinkedHashMultiset::create,
        (multiset, t) ->
            multiset.add(checkNotNull(elementFunction.apply(t)), countFunction.applyAsInt(t)),
        (multiset1, multiset2) -> {
          multiset1.addAll(multiset2);
          return multiset1;
        },
        (Multiset<E> multiset) -> ImmutableMultiset.copyFromEntries(multiset.entrySet()));
  }

   * <p>If the mapped elements contain duplicates (according to {@code comparator}), the first
   * occurrence in encounter order appears in the resulting multiset, with count equal to the sum of
   * the outputs of {@code countFunction.applyAsInt(t)} for each {@code t} mapped to that element.
   *
   * @since 22.0
   */
  public static <T extends @Nullable Object, E>
      Collector<T, ?, ImmutableSortedMultiset<E>> toImmutableSortedMultiset(

   * occurrence in encounter order appears in the resulting multiset, with count equal to the sum of
   * the outputs of {@code countFunction.applyAsInt(t)} for each {@code t} mapped to that element.
   *
   * @since 22.0
   */
  public static <T extends @Nullable Object, E>
      Collector<T, ?, ImmutableMultiset<E>> toImmutableMultiset(