Validator Component in a standalone project

EntityValidator.php

<?php
namespace Company\Entity;

use Symfony\Component\Validator\ConstraintViolationListInterface;
use Symfony\Component\Validator\ConstraintViolationInterface;
use Symfony\Component\Validator\Validator\ValidatorInterface;

abstract class EntityValidator
{
    public function validate(ValidatorInterface $validator, array $groups = array())
    {
        return $this->parseValidationMessages(
            $validator->validate($this, $groups)
        );
    }
    
    private function parseValidationMessages(ConstraintViolationListInterface $messages)
    {
        if (count($messages) == 0) {
            return array();
        }

        $errors = array();
        /** @var ConstraintViolationInterface $message */
        foreach ($messages as $message) {
            $propertyPath = $message->getPropertyPath();
            if (empty($propertyPath) && is_object($message->getInvalidValue())) {
                $propertyPath = "class";
            }

            $errors[$propertyPath][] = $message->getMessage();
        }

        return $errors;
    }
}

UserEntity.php

<?php
namespace Company\User;

use Symfony\Component\Validator\Constraints as Assert;
use Company\Entity\EntityValidator;

class UserEntity extends EntityValidator
{
    /**
     * @var string
     *
     * @Assert\NotBlank(
     *      message = "The username should not be empty!",
     *      groups = {"insert", "update"}
     * )
     */
    protected $username;
}

ValidatorFactory.php

<?php
namespace Company\Services;

use Doctrine\Common\Annotations\AnnotationReader;
use Doctrine\Common\Annotations\AnnotationRegistry;
use Doctrine\Common\Annotations\CachedReader;
use Doctrine\Common\Cache\FilesystemCache;
use Symfony\Component\Translation\Translator;
use Symfony\Component\Validator\Validation;

class ValidatorFactory
{
    private $translator;
    private $config;
    private $debug;
    
    public function __construct(Translator $translator, array $config, $debug = false)
    {
        $this->translator = $translator;
        $this->config = $config;
        $this->debug = $debug;
    }
    
    public function getValidator()
    {
        $builder = Validation::createValidatorBuilder();

        $builder->setTranslator($this->translator);
        $builder->setTranslationDomain("constraints");

        AnnotationRegistry::registerAutoloadNamespace(
            "Symfony\\Component\\Validator\\Constraint",
            realpath($this->config['source'] . "_vendor" . DS . "symfony" . DS . "validator" . DS)
        );

        $annotationReader = new AnnotationReader();
        $cache = new FilesystemCache($this->config['cache']);
        $builder->enableAnnotationMapping(new CachedReader($annotationReader, $cache, true));

        return $builder->getValidator();
    }
}