public void testNulls_enum() throws Exception {
    tester.testNulls(OneConstantEnum.class);
    tester.testNulls(NoConstantEnum.class);
    tester.testNulls(TimeUnit.class);
  }

  public void testNulls_parameterOptionalNotInstantiable() throws Exception {
    tester.testNulls(ConstructorParameterWithOptionalNotInstantiable.class);
  }

  public void testEnumFailsToCheckNull() throws Exception {
    try {