public function serialize(Paper $paper, array $options = [])
    {
        // Adds user score if available and the method options do not already request it
        if (!in_array(Transfer::INCLUDE_USER_SCORE, $options)
            && $this->isScoreAvailable($paper->getExercise(), $paper)) {
            $options[] = Transfer::INCLUDE_USER_SCORE;
        }

        return $this->serializer->serialize($paper, $options);
    }