docs: private ValidatorFactory createValidatorFactory(FacesContext context)
      {
          Map<String, Object> applicationMap = context.getExternalContext().getApplicationMap();
          Object attr = applicationMap.get(VALIDATOR_FACTORY_KEY);
          if (attr instanceof ValidatorFactory)
          {
              return (ValidatorFactory) attr;
          }
          else
          {
              synchronized (this)
              {
                  if (_ExternalSpecifications.isBeanValidationAvailable())
                  {
                      ValidatorFactory factory = Validation.buildDefaultValidatorFactory();
                      applicationMap.put(VALIDATOR_FACTORY_KEY, factory);
                      return factory;
                  }
                  else
                  {
                      throw new FacesException("Bean Validation is not present");
                  }
              }
          }
      }