### Question:
Validator { public static void validateQueue(String queue) { if (StringUtils.isEmpty(queue)) { throw new IllegalArgumentException("queue cannot be empty"); } } private  Validator(); static void validateMessage(Object message); static void validateMessageId(String messageId); static void validateRetryCount(int retryCount); static void validateDelay(long delayInMilliSecs); static void validateQueue(String queue); static void validatePriority(String priority);  }### Answer:
@Test public void validateQueue() { assertThrows(IllegalArgumentException.class, () -> Validator.validateQueue(null)); }