@Override
    public Builder<E> addAll(Iterable<? extends E> elements) {
      if (elements instanceof Multiset) {
        Multiset<? extends E> multiset = Multisets.cast(elements);
        multiset.forEachEntry((e, n) -> contents.add(checkNotNull(e), n));
      } else {
        super.addAll(elements);
      }
      return this;
    }

    /**

    ImmutableSortedMultiset<String> multiset =
        ImmutableSortedMultiset.<String>naturalOrder().add("a").add("b").add("a").add("c").build();
    List<Multiset.Entry<String>> entries = new ArrayList<>();
    multiset.forEachEntry((e, c) -> entries.add(Multisets.immutableEntry(e, c)));
    assertThat(entries)
        .containsExactly(
            Multisets.immutableEntry("a", 2),
            Multisets.immutableEntry("b", 1),

          return entrySpliterator();
        }

        @Override
        public void forEach(Consumer<? super Entry<K, V>> action) {
          forEachEntry(action);
        }
      };
    }

    void forEachEntry(Consumer<? super Entry<K, V>> action) {
      entryIterator().forEachRemaining(action);
    }

    @Override
    public void clear() {