EasyAdminBundle: `validation_groups` is ignored

When I have this in my entity:

/**
 * @ORM\Column(type="string", length=255, nullable=true)
 * @Assert\NotBlank(groups={"foo"})
 */
private $firstName;

…and this in easy_admin.yaml:

easy_admin:
    entities:
        User:
            class: App\Entity\User
            form:
                form_options: { validation_groups: ['Default'] }

…I’m getting the field marked as required.

easycorp/easyadmin-bundle 2.1.1