code: def update_payload(self, fields=None):
          
          payload = super(OSDefaultTemplate, self).update_payload(fields)
          return {'os_default_template': payload}
docs: Wrap payload in ``os_default_template``
          relates to `Redmine #21169`_.
  
          .. _Redmine #21169: http://projects.theforeman.org/issues/21169