How to group form validation in Symfony 4.4.8?

Question

symfony

There was a question: I have such a form

namespace App\Form;

use Symfony\Component\Form\AbstractType;
use Symfony\Component\Form\FormBuilderInterface;
use Symfony\Component\OptionsResolver\OptionsResolver;
use Symfony\Component\Form\Extension\Core\Type\EmailType;
use Symfony\Component\Form\Extension\Core\Type\DateTimeType;
use Symfony\Component\Form\Extension\Core\Type\TextType;
use Symfony\Component\Form\Extension\Core\Type\PasswordType;
use Symfony\Component\Validator\Constraints\Length;
use Symfony\Component\Validator\Constraints\Url;
/**
 * Class CommonFieldType
 * Implements adjacent fields for the short link form and the file upload form
 * @package App\Form
 */
class CommonFieldType extends AbstractType
{
    public function buildForm(FormBuilderInterface $builder, array $options)
    {
        $builder
            ->add('url',TextType::class,['constraints' => new Url()])
        ;
    }

    public function configureOptions(OptionsResolver $resolver)
    {
        $resolver->setDefaults([
            // Configure your form options here
        ]);
    }
}

Symfony has a standard filter for checking url

Symfony\Component\Validator\Constraints\Url

To use it I write

['constraints' => new Url()]

But I need to check more max length how to do it? There is such a way

['constraints' => new Length(['max' => 255])]

But the field can still be empty. But how do I combine these three checks? That is, the condition for checking the form: if it is not empty, check for the validity of the url and for the length. The official documentation says

If you are using validation groups, you need to either reference the Default group when creating the form, or set the correct group on the constraint you are adding: new NotBlank(['groups' => ['create', 'update'] ]);

But to be honest, it did not help me at all, tell me how to do it?