@Test
 public void testGetAsMissing() {
   final Configuration configuration = TestConfiguration.createNull();
   @SuppressWarnings("unchecked")
   final Map<String, String> value =
       (Map<String, String>) configuration.getAs(Map.class, Collections.emptyMap());
   Assert.assertTrue(value.isEmpty());
 }
 @Test(expected = NoSuchElementException.class)
 public void testGetRequiredAsMissing() {
   final Configuration configuration = TestConfiguration.createNull();
   configuration.getRequiredAs(Map.class);
 }