code: protected void verifyDefaultGroupClientError(Object form) {
          // e.g. @Required(groups = { ClientError.class }) (when default group specified)
          if (containsRuntimeGroup(runtimeGroups, DEFAULT_GROUP_TYPE)) {
              final Set<ConstraintViolation<Object>> clientErrorSet = hibernateValidate(form, CLIENT_ERROR_GROUPS);
              handleClientErrorViolation(form, clientErrorSet);
          }
      }
docs: ============