### Question:
Annotations implements Iterable<Annotation> { public boolean contains(Class<? extends Annotation> type) { if (type == null) { throw new IllegalArgumentException("Method argument type must not be null."); } return getAnnotationMap().get(type) != null; } Annotations(AnnotatedElement annotatedElement); static Annotations annotations(AnnotatedElement annotatedElement); boolean contains(Class<? extends Annotation> type); boolean containsName(String name); @SuppressWarnings("unchecked") T get(Class<T> type); Stream<Annotation> stream(); @Override @Nonnull Iterator<Annotation> iterator(); Map<Class<? extends Annotation>, Annotation> getAnnotations();  }### Answer:
@Test(expected = IllegalArgumentException.class) public void testHandlingOfNullElementArgumentForExistenceTest() { this.testee.contains(null); }