code: func (p *partitions) shutdown() {
  	p.Lock()
  	defer p.Unlock()
  	if p.isShutdown {
  		return
  	}
  	p.isShutdown = true
  	if p.nc != nil {
  		p.nc.Close()
  	}
  }
docs: // Notifies all go-routines used by partitioning code that the
  // server is shuting down and closes the internal NATS connection.