code: public void afterPropertiesSet() throws Exception {
          if (target == null) {
              throw new IllegalArgumentException(
                      "Property 'target' must be set.'");
          }
  
          if (defaultUser == null) {
              throw new IllegalArgumentException(
                      "Property 'defaultUser' must be set.'");
          }
  
          if (defaultPassword == null) {
              throw new IllegalArgumentException(
                      "Property 'defaultPassword' must be set.'");
          }
      }
docs: /*
  (non-Javadoc)
  
  @see org.springframework.beans.factory.InitializingBean#afterPropertiesSet()