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) {

  }

  static boolean removeAllImpl(Set<?> set, Collection<?> collection) {
    checkNotNull(collection); // for GWT
    if (collection instanceof Multiset) {
      collection = ((Multiset<?>) collection).elementSet();
    }
    /*
     * AbstractSet.removeAll(List) has quadratic behavior if the list size
     * is just more than the set's size.  We augment the test by

        }
      }
      return oldCount;
    }

    @Override
    public void clear() {
      multimap.clear();
    }

    @Override
    public Set<K> elementSet() {
      return multimap.keySet();
    }

    @Override
    Iterator<K> elementIterator() {
      throw new AssertionError("should never be called");
    }
  }