/** @see org.springframework.beans.factory.InitializingBean#afterPropertiesSet() */
 public void afterPropertiesSet() {
   Assert.hasText(
       casValidateUrl, "property [casValidateUrl] of class [" + getClass() + "] can not be null");
   Assert.hasText(service, "property [service] of class [" + getClass() + "] can not be null");
   Assert.hasText(
       proxyCallbackUrl,
       "property [proxyCallbackUrl] of class [" + getClass() + "] can not be null");
   if (retries == null || retries < 0) {
     retries = 0;
   }
   if (sleep == null || sleep < 0) {
     sleep = 1;
   }
 }