Settings group_name cannot be specified in api.setting.create.

api.setting.create does not allow the setting group_name to be specified. As there is no uniqueness requirement on the names of settings, calling api.setting.create will result in all settings with that name being updated.

The combination of group_name and name is required to be unique, however. Allowing API users to specify the group will enable a greater level of specificity. As the extension ecosystem grows, it is more likely that extensions will use non-unique setting names.

Note: The problem is not in the API per se, but the underlying BAO.