Symfony2 FOSUser自定义验证不起作用

fos_user:
    # ...
    registration:
        form:
            validation_groups: [Registration, Default]

use Symfony\Component\Validator\Constraint;

/**
 * @Annotation
 */
class CustomValidation extends Constraint
{
    public $message = 'Custom validation failed.';
    
    public function validatedBy()
    {
        return get_class($this).'Validator';
    }
}

use Symfony\Component\Validator\Constraint;
use Symfony\Component\Validator\ConstraintValidator;

class CustomValidationValidator extends ConstraintValidator
{
    public function validate($value, Constraint $constraint)
    {
        // 自定义验证逻辑
        if ($value !== 'custom') {
            $this->context->buildViolation($constraint->message)
                ->setParameter('{{ value }}', $value)
                ->addViolation();
        }
    }
}

use Symfony\Component\Form\AbstractType;
use Symfony\Component\Form\FormBuilderInterface;
use Symfony\Component\OptionsResolver\OptionsResolver;
use Symfony\Component\Validator\Constraints as Assert;
use AppBundle\Validator\CustomValidation;

class RegistrationType extends AbstractType
{
    public function buildForm(FormBuilderInterface $builder, array $options)
    {
        $builder
            // ...
            ->add('customField', null, [
                'constraints' => [
                    new Assert\NotBlank(),
                    new CustomValidation(),
                ],
            ])
            // ...
        ;
    }

    // ...
}