public void MQTTPublishMessage(string topic, byte[] payload) { topic = topic.Replace("//", "/"); var message = new MqttApplicationMessageBuilder() .WithTopic(topic) .WithPayload(payload) .WithExactlyOnceQoS() .WithRetainFlag() .Build(); Debug.Log("newClient publishes message: " + topic); client.PublishAsync(message); currentlyProcessingMessages.Add(message.GetHashCode()); }