@Override
        public boolean addListener(ChannelListener<T> listener) {
            Preconditions.checkState(this.channel != null, "agent not active");
            try {
                return this.listeners.add(listener);
            } finally {
                this.channel.checkSubscription();
            }
        }
Distributes an oncoming message to the channels held in this messenger.

@param channel the channel the message was received on
@param message the message
helper/src/main/java/me/lucko/helper/messaging/AbstractMessenger.java