### Question:
HashBag implements MutableBag<T> { @Override public Iterator<T> iterator() { return new BagIterator(); }  @Override int sizeDistinct(); @Override int size(); @Override boolean isEmpty(); @Override boolean contains(Object o); @Override Object[] toArray(); void forEachWithIndex(BiConsumer<? super T, Integer> biConsumer); @Override T1[] toArray(T1[] array); @Override boolean add(T element); @Override boolean remove(Object o); @Override boolean containsAll(Collection<?> c); @Override boolean addAll(Collection<? extends T> c); @Override boolean removeAll(Collection<?> c); @Override boolean retainAll(Collection<?> c); @Override void clear(); @Override Iterator<T> iterator(); @Override int getOccurrences(T element); @Override boolean addOccurrence(T element); @Override boolean addOccurrences(T element, int occurrences); @Override boolean removeOccurrence(T element); @Override boolean removeOccurrences(T element, int occurrences); @Override void forEachWithOccurrences(BiConsumer<? super T, Integer> biConsumer); @Override void forEach(Consumer<? super T> consumer); @Override int hashCode(); @Override boolean equals(Object other);  }### Answer:
@Test public void iterator() { this.testObj.withAll("1", "2", "3", "2", "3", "3"); Iterator<String> iterator = this.testObj.iterator(); Assert.assertEquals("1", iterator.next()); Assert.assertTrue(iterator.hasNext()); iterator.remove(); Assert.assertEquals("2", iterator.next()); iterator.remove(); Assert.assertEquals("2", iterator.next()); Assert.assertEquals("3", iterator.next()); iterator.remove(); Assert.assertEquals("3", iterator.next()); iterator.remove(); Assert.assertEquals("3", iterator.next()); iterator.remove(); Assert.assertFalse(iterator.hasNext()); Assert.assertEquals(MutableBag.of("2"), this.testObj); }