### Question:
WrappingSimpleCollection implements SimpleCollection<E> { @Override public Stream<E> stream() { return delegateCollection.stream(); } 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 stream() { final Stream<String> stream = simpleCollection.stream(); final List<String> streamed = stream.collect(Collectors.toList()); assertEquals(3, streamed.size()); assertEquals("a", streamed.get(0)); assertEquals(null, streamed.get(1)); assertEquals("b", streamed.get(2)); }