guava/src/com/google/common/collect/Multisets.java
static <E> Iterator<E> iteratorImpl(Multiset<E> multiset) {
    return new MultisetIteratorImpl<E>(multiset, multiset.entrySet().iterator());
  }
static <E> Iterator<E> iteratorImpl(Multiset<E> multiset) {
    return new MultisetIteratorImpl<E>(multiset, multiset.entrySet().iterator());
  }
An implementation of {@link Multiset#iterator}.