@Test
 public void shouldOnlyValidateStrings() {
   {
     boolean valid = validator.isValid("44474042000130", context);
     assertTrue(valid);
   }
 }
 @Test
 public void shouldValidateEmpty() {
   boolean valid = validator.isValid("", context);
   assertTrue(valid);
 }
 @Test
 public void shouldValidateNull() {
   boolean valid = validator.isValid(null, context);
   assertTrue(valid);
 }
 @Before
 public void createValidator() throws Exception {
   CNPJ cnpjAnnotation = ObjectWithCNPJ.class.getDeclaredField("cnpj").getAnnotation(CNPJ.class);
   validator = new StellaCNPJValidator();
   validator.initialize(cnpjAnnotation);
 }