void processUnsubscribe(ServerChannel session, String clientID, List<String> topics, int messageID) {
        Log.trace("processUnsubscribe invoked, removing subscription on topics {}, for clientID <{}>", topics, clientID);

        for (String topic : topics) {
            subscriptions.removeSubscription(topic, clientID);
        }
        //ack the client
        UnsubAckMessage ackMessage = new UnsubAckMessage();
        ackMessage.setMessageID(messageID);

        Log.trace("replying with UnsubAck to MSG ID {}", messageID);
        session.write(ackMessage);
    }
void processUnsubscribe ( ServerChannel session , String clientID , List < String > topics , int messageID ) { Log . trace ( "processUnsubscribe invoked, removing subscription on topics {}, for clientID <{}>" , topics , clientID ) ; for ( String topic : topics ) { subscriptions . removeSubscription ( topic , clientID ) ; } UnsubAckMessage ackMessage = new UnsubAckMessage ( ) ; ackMessage . setMessageID ( messageID ) ; Log . trace ( "replying with UnsubAck to MSG ID {}" , messageID ) ; session . write ( ackMessage ) ; }
Remove the clientID from topic subscription, if not previously subscribed,
doesn't reply any error