@Test
 public void loadNonExistentUntypedClass() {
   try {
     propertiesNotFoundConfig.getNonExistentUntypedClass();
     fail();
   } catch (ConfigurationException cause) {
     assertEquals(ClassNotFoundException.class, cause.getCause().getClass());
   }
 }
 @Test
 public void loadUntypedClassFromEmptyKey() {
   try {
     propertiesEmptyFieldConfig.getEmptyUntypedClass();
     fail();
   } catch (ConfigurationException cause) {
     assertEquals(ClassNotFoundException.class, cause.getCause().getClass());
   }
 }