private function validateParamBundleList(array $paramBundleList, $serverField)
    {
        foreach ($paramBundleList as $paramBundle) {
            try {
                $this->validateParamBundle($paramBundle);
            } catch (InvalidVariantException $e) {
                // Rethrow exception only if the field was provided by the server
                if ($serverField) {
                    throw $e;
                }
            }
        }
    }