When using the Content Selector Privilege creation REST API, both a Repository and Format field are mandatory but the Format field seems to be ignored.
Both fields are validated and can be a specific value (Formats not actually documented) or a wildcard *. However, although the format field must be compatible with the Repository value, it will be ignored.
Passing a wildcard for the Repository and a specific (maven2) value for the Format will not create a Content Selector Privilege for all Maven 2 Repositories as expected, but will simply create an All Repositories privilege.
The fields should work as expected, and those expectations also be documented.