Twig email templates

In Class WebformSubmission The $data variable is protected hence you cannot access the webform_submission within a twig template.

class WebformSubmission extends ContentEntityBase implements WebformSubmissionInterface {
protected $data = [];
}

webform\templates\webform-email-message-html.html.twig

Twig templates override files for emails notifications for hardcoding email templates as files.

{#
/**
* @file
* Default theme implementation for webform email wrapper template as HTML.
*
* Available variables:
* - message: The email message which contains to, from, subject, message, etc…
* - webform_submission: The webform submission.
* - handler: The webform handler.
*
* @ingroup themeable
*/
#}
{{ message.body }}

Am i missing something?