Como prefixar nomes de sequência?

parameters:
    mybundle.db.sequence_prefix: myprefix_

services:
    mybundle.sqprefix_subscriber:
        class: MyBundle\Subscriber\SequencePrefixSubscriber
        arguments: [%mybundle.db.sequence_prefix%]
        tags:
            - { name: doctrine.event_subscriber }

<?php
namespace MyBundle\Subscriber;

use Doctrine\ORM\Event\LoadClassMetadataEventArgs;

class SequencePrefixSubscriber implements \Doctrine\Common\EventSubscriber
{
    protected $prefix = '';

    public function __construct($prefix)
    {
        $this->prefix = (string) $prefix;
    }

    public function getSubscribedEvents()
    {
        return array('loadClassMetadata');
    }

    public function loadClassMetadata(LoadClassMetadataEventArgs $args)
    {
        $classMetadata = $args->getClassMetadata();
        if ($classMetadata->isInheritanceTypeSingleTable() && !$classMetadata->isRootEntity()) {
            return;
        }


        if ($classMetadata->isIdGeneratorSequence())
        {
            $newDefinition = $classMetadata->sequenceGeneratorDefinition;
            $newDefinition['sequenceName'] = $this->prefix . $newDefinition['sequenceName'];

            $classMetadata->setSequenceGeneratorDefinition($newDefinition);
            $em = $args->getEntityManager();
            if (isset($classMetadata->idGenerator)) {
                $sequenceGenerator = new \Doctrine\ORM\Id\SequenceGenerator(
                    $em->getConfiguration()->getQuoteStrategy()->getSequenceName(
                        $newDefinition,
                        $classMetadata,
                        $em->getConnection()->getDatabasePlatform()),
                    $newDefinition['allocationSize']
                );
                $classMetadata->setIdGenerator($sequenceGenerator);
            }
        }
    }
}