abandon method
Returnes message into the queue and makes it available for all subscribers to receive it again. This method is usually used to return a message which could not be processed at the moment to repeat the attempt. Messages that cause unrecoverable errors shall be removed permanently or/and send to dead letter queue.
Important: This method is not supported by MQTT.
message
a message to return. Returns (optional) Future that receives an null for success. Throws error
Implementation
@override
Future abandon(MessageEnvelope message) async {
// Not supported
return null;
}