code: func (o *ClientOptions) SetOrderMatters(order bool) *ClientOptions {
  	o.Order = order
  	return o
  }
docs: // SetOrderMatters will set the message routing to guarantee order within
  // each QoS level. By default, this value is true. If set to false,
  // this flag indicates that messages can be delivered asynchronously
  // from the client to the application and possibly arrive out of order.