code: public void resolveFactoryBeanClass(BeanRule beanRule) throws IllegalRuleException {
          String beanIdOrClass = beanRule.getFactoryBeanId();
          if (beanRule.isFactoryOffered() && beanIdOrClass != null) {
              Class<?> beanClass = resolveBeanClass(beanIdOrClass, beanRule);
              if (beanClass != null) {
                  beanRule.setFactoryBeanClass(beanClass);
                  reserveBeanReference(beanClass, beanRule);
              } else {
                  reserveBeanReference(beanIdOrClass, beanRule);
              }
          }
      }
docs: Resolve bean class for factory bean rule.
  
  @param beanRule the bean rule
  @throws IllegalRuleException if an illegal rule is found