@Test
 public void testCreateDoubleGenerator_notUnique() {
   Generator<Double> generator = fcn.createNumberGenerator(Double.class, 1., 2., 0.5, false);
   generator.init(context);
   int n = 2000;
   Map<Double, AtomicInteger> counts = super.countProducts(generator, n);
   assertEquals(3, counts.size());
   int lastCount = n + 1;
   for (double d = 1; d <= 2; d += 0.5) {
     int count = counts.get(d).intValue();
     assertTrue(count < lastCount);
     lastCount = count;
   }
 }
 @Test(expected = IllegalArgumentException.class)
 public void testCreateDoubleGenerator_unique() {
   fcn.createNumberGenerator(Double.class, 1., 4., 0.5, true);
 }