Change record status: 
Introduced in branch: 
3.0.x
Introduced in version: 
3.0.0-beta1
Description: 

The constraint classes, introduced in Replace UserRestrictionEditForm::validateForm() with an entity constraint and The entered pattern is not validated, are not part of the public API. As such, no contributed project should not extend them.
In the 4.0.x branch, they will be marked final.

Impacts: 
Module developers
Site templates, recipes and distribution developers