manual acknowledgement results in duplicate pubcomp

[whizyrel]

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• Bug exists Release Version 1.2.5 ( Master Branch)
• Bug exists in MQTTv3 Client on Snapshot Version 1.2.6-SNAPSHOT (Develop Branch)
• Bug exists in MQTTv5 Client on Snapshot Version 1.2.6-SNAPSHOT (Develop Branch)

If this is a bug regarding the Android Service, please raise the bug here instead: https://github.com/eclipse/paho.mqtt.android/issues/new

ISSUE DESCRIPTION
Setting manual acknowledgement to true and calling the message arrived complete method results into duplicate pubcomp and the connection gets disconnected. In short, manual acknowledgement is not possible.

SNIPPET TO REPRODUCE

var client = ...;

client.setManualAcks(true);

client.setCallback(new MqttCallback() {
   ...
   @Override
   public void messageArrived(String topic, MqttMessage message) {
      ...
      client.messageAriveComplete(message.getId(), 2);
      ...
   }
   ...
});

client.subscribe(...);

Result

Creating MqttPubComp due to manual ACK: MqttPubComp [returnCode=0, properties=MqttProperties [validProperties=[...]]]
Creating MqttPubComp: MqttPubComp [returnCode=0, properties=MqttProperties [validProperties=[...]]]
MqttDisconnectResponse [returnCode=0, reasonString=null, userProperties=null, serverReference=null, exception=Connection lost (32109) - java.net.SocketException: Connection reset]