### Question:
CollectionUtils { public static boolean isEmpty(final Collection<?> collection) { if (collection == null) { return true; } return collection.isEmpty(); } private  CollectionUtils(); static String toString(final Collection<?> collection); static int getLastIndex(final Collection<?> collection); static boolean isEmpty(final Collection<?> collection);  }### Answer:
@Test public void testIsEmpty() { Assert.assertTrue(CollectionUtils.isEmpty(null)); List<String> list = new ArrayList<String>(); Assert.assertTrue(CollectionUtils.isEmpty(list)); list.add("1"); Assert.assertFalse(CollectionUtils.isEmpty(list)); list.add("2"); Assert.assertFalse(CollectionUtils.isEmpty(list)); list.add("4"); Assert.assertFalse(CollectionUtils.isEmpty(list)); list.clear(); Assert.assertTrue(CollectionUtils.isEmpty(list)); }