public void detach(NetworkOwner owner) {
        if ( ! owners.remove(owner))
            throw new IllegalArgumentException(owner + " not attached to " + this);

        destroyIfOwnerless();
    }
Detach the network owner from this, no longer allowing messages to it, and shutting down this is ownerless.
messagebus/src/main/java/com/yahoo/messagebus/network/NetworkMultiplexer.java