code: func NewNotifyingWorkitemsController(service *goa.Service, db application.DB, notificationChannel notification.Channel, config WorkItemControllerConfig) *WorkitemsController {
  	n := notificationChannel
  	if n == nil {
  		n = &notification.DevNullChannel{}
  	}
  	return &WorkitemsController{
  		Controller:   service.NewController("WorkitemController"),
  		db:           db,
  		notification: n,
  		config:       config}
  }
docs: // NewNotifyingWorkitemsController creates a workitem controller with notification broadcast.