public function serializeItems(Step $step, array $options = [])
    {
        return array_values(array_map(function (StepItem $stepQuestion) use ($options) {
            $serialized = $this->itemSerializer->serialize($stepQuestion->getQuestion(), $options);
            $serialized['meta']['mandatory'] = $stepQuestion->isMandatory();

            return $serialized;
        }, $step->getStepQuestions()->toArray()));
    }