How are global roles synced with group roles? How are global roles synced with group roles in the Drupal 8 group module?

I expect that the module would either:


Create a group roles in each group type for each global role


and/or one of the below:


Create role assignments for users in the group who have a global role that matches a group role name.
Assign global roles for users who have a group role in any group where the group role name matches a global role name.


In my testing so far it appears to do none of the above.

The group role sub-module is marked as deprecated and has a note that the functionality is in the core group module. A code review shows that the sub-module is basically empty. Therefore I take it the note is correct. I also see that the group module implements hook_rebuild and it creates a config entity for each global role.

None of the above expected results are happening however.
Take a look at the roles &amp; permissions page for a group (and also group's documentation). By default groups treats all authenticated non-members as outsiders no matter what their role is, but there is an advanced option to define permissions based on their global drupal roles.