private function getOperations(\SimpleXMLElement $resource, string $operationType): ?array
    {
        $graphql = 'operation' === $operationType;
        if (!$graphql && $legacyOperations = $this->getAttributes($resource, $operationType)) {
            @trigger_error(
                sprintf('Configuring "%1$s" tags without using a parent "%1$ss" tag is deprecated since API Platform 2.1 and will not be possible anymore in API Platform 3', $operationType),
                E_USER_DEPRECATED
            );

            return $legacyOperations;
        }

        $operationsParent = $graphql ? 'graphql' : "{$operationType}s";
        if (!isset($resource->{$operationsParent})) {
            return null;
        }

        return $this->getAttributes($resource->{$operationsParent}, $operationType, true);
    }