空变量FormValidation错误Symfony表单构建器

I can't pass a null value through the validation of my form, this is my code (I'll only show you the necessary part of the code) :

Form :

/**
 * @param FormBuilderInterface $builder
 * @param array $options
 */
public function buildForm(FormBuilderInterface $builder, array $options)
{
    parent::buildForm($builder, $options);
    $builder
        ->add('text', TextType::class , array(
            'required' => false,
            'empty_data' => null,
        ))
}

My entity (it's a Trait) :

trait TextTrait
{
    /**
     * @ORM\Column(type="text", nullable=true)
     */
    private $text = null;

    /**
     * Set text
     *
     * @param string $text
     */
    public function setText(?string $text = null)
    {
        $this->text = $text;

        return $this;
    }

    /**
     * Get text
     *
     * @return string
     */
    public function getText() : ?string
    {
        return $this->text;
    }
}

The error :

How can i pass a null variable in a symfony form ??