@Override
 public T getRandomValue() {
   Integer randomPercent = aNewIntegerRangeRandomizer(0, MAX_PERCENT - 1).getRandomValue();
   if (randomPercent <= optionalPercent) {
     return delegate.getRandomValue();
   }
   return null;
 }
 @Before
 public void setUp() throws Exception {
   when(randomizer.getRandomValue()).thenReturn(NAME);
 }