Expose user who created the invoice in the invoice template (v5)

By law in my country an invoice must contain identification of the person who issued it (in the invoice details block), either by name or some other identification (that could be placed in the custom field for the user).

In previous versions there was a $user object variable and is still listed on the fronted side when designing invoice, even though it is not set (_app/Utils/HtmlEngine.php_)

Could this be implemented by exposing user details object in the template? "$user" or "$issuer" variable?