docs: def update_roster(self, REQUEST=None):
          """
          If workspace is team managed, users can add/remove participants.
          Any user with the manage workspace permission can add/remove
          participants and admins.
          """
          CheckAuthenticator(self.request)
          PostOnly(self.request)
          form = self.request.form
          entries = form.get('entries', [])
          self.update_users(entries)
          api.portal.show_message(message=_(u'Roster updated.'),
                                  request=self.request)
          return self.request.response.redirect(
              '%s/@@edit-roster' % self.context.absolute_url())