*
   * <p>A common use for the element set is to find the number of distinct elements in the multiset:
   * {@code elementSet().size()}.
   *
   * @return a view of the set of distinct elements in this multiset
   */
  Set<E> elementSet();

  /**
   * Returns a view of the contents of this multiset, grouped into {@code Multiset.Entry} instances,

        return delegate().setCount(element, oldCount, newCount);
      }
    }

    @Override
    public Set<E> elementSet() {
      synchronized (mutex) {
        if (elementSet == null) {
          elementSet = typePreservingSet(delegate().elementSet(), mutex);
        }
        return elementSet;
      }
    }

    @Override
    public Set<Multiset.Entry<E>> entrySet() {
      synchronized (mutex) {

        return delegate().setCount(element, oldCount, newCount);
      }
    }

    @Override
    public Set<E> elementSet() {
      synchronized (mutex) {
        if (elementSet == null) {
          elementSet = typePreservingSet(delegate().elementSet(), mutex);
        }
        return elementSet;
      }
    }

    @Override
    public Set<Multiset.Entry<E>> entrySet() {
      synchronized (mutex) {

        @Override
        Iterator<Entry<E>> entryIterator() {
          return backingMultiset.descendingMultiset().entrySet().iterator();
        }
      };
    }

    @Override
    public NavigableSet<E> elementSet() {
      return new StandardElementSet();
    }

    @Override
    public Entry<E> firstEntry() {
      return standardFirstEntry();
    }

    @Override
    public Entry<E> lastEntry() {

    // TODO(kevinb): see if we can share code with OrderedIterator after it
    // graduates from labs.
    if (targets instanceof Multiset) {
      targets = ((Multiset<?>) targets).elementSet();
    }
    if (!SortedIterables.hasSameComparator(comparator(), targets) || (targets.size() <= 1)) {
      return super.containsAll(targets);
    }

    /*

          parentBuilder) {
    // TODO(lowasser): make a SortedElementSetGenerator
    return SetTestSuiteBuilder.using(
            new ElementSetGenerator<E>(parentBuilder.getSubjectGenerator()))
        .named(getName() + ".elementSet")
        .withFeatures(computeElementSetFeatures(parentBuilder.getFeatures()))
        .suppressing(parentBuilder.getSuppressedTests())
        .createTestSuite();
  }

  /**

    } catch (UnsupportedOperationException expected) {
    }
    assertCollectionsAreEquivalent(multiset, copy);

    assertSetIsUnmodifiable(multiset.elementSet(), sampleElement);
    assertCollectionsAreEquivalent(multiset, copy);

    assertSetIsUnmodifiable(
        multiset.entrySet(),
        new Multiset.Entry<E>() {
          @Override

    } catch (UnsupportedOperationException expected) {
    }
    assertCollectionsAreEquivalent(multiset, copy);

    assertCollectionsAreEquivalent(multiset, copy);

    assertSetIsUnmodifiable(multiset.elementSet(), sampleElement);
    assertCollectionsAreEquivalent(multiset, copy);

    assertSetIsUnmodifiable(
        multiset.entrySet(),
        new Multiset.Entry<E>() {
          @Override

 *       ordering is otherwise specified (e.g. {@link ImmutableSortedSet#naturalOrder}). See the
 *       appropriate factory method for details. View collections such as {@link
 *       ImmutableMultiset#elementSet} iterate in the same order as the parent, except as noted.
 *   <li><b>Thread safety.</b> It is safe to access this collection concurrently from multiple
 *       threads.

    @Override
    public int count(@Nullable Object element) {
      Collection<V> values = map.get(element);
      return (values == null) ? 0 : values.size();
    }

    @Override
    public ImmutableSet<K> elementSet() {
      return keySet();
    }

    @Override
    public int size() {
      return ImmutableMultimap.this.size();
    }

    @Override
    Multiset.Entry<K> getEntry(int index) {