@Test
	public void testNullIsOk() {
		Bean bean = new Bean();
		Set<ConstraintViolation<Bean>> violations = validator.validate(bean);
		Assert.assertThat(violations, Matchers.empty());
	}
Tests for DateFormat.DateFormatValidator.

@author Eric Bottard
spring-xd-module-spi/src/test/java/org/springframework/xd/module/options/validation/DateFormatValidatorTests.java