Doctrine\ODM\MongoDB\Aggregation\Stage\Out::fromDocument PHP Method

    private function fromDocument(ClassMetadata $classMetadata)
    {
        if ($classMetadata->isSharded()) {
            throw MappingException::cannotUseShardedCollectionInOutStage($classMetadata->name);
        }
        return parent::out($classMetadata->getCollection());
    }