'Callback, clears user default_project_id after project deletion.
Notifications are used to unset a user\'s default project because
there is no foreign key to the project. Projects can be in a non-SQL
backend, making FKs impossible.'

def _unset_default_project(self, service, resource_type, operation, payload):

    project_id = payload['resource_info']
    try:
        self.driver.unset_default_project_id(project_id)
    except exception.Forbidden:
        pass
