### Question:
WrappingSimpleCollection implements SimpleCollection<E> { @Override public Iterator<E> iterator() { return new NonNullIterator<>(delegateCollection.iterator()); } WrappingSimpleCollection(Collection<E> delegateCollection); @Override int size(); @Override boolean isEmpty(); @Override Iterator<E> iterator(); @Override Iterator<E> structuralIterator(); @Override Stream<E> stream();  }### Answer:
@Test public void iterator() { final Iterator<String> iterator = simpleCollection.iterator(); assertEquals("a", iterator.next()); assertEquals("b", iterator.next()); assertFalse(iterator.hasNext()); }