public void multiplexerAvailable(String connectionManagerName) {
        // Add a new entry in the list of available managers. Here is where we are going to store
        // which clients were connected through which connection manager
        sessionsByManager.computeIfAbsent(connectionManagerName, e -> new ConcurrentHashMap<>());
    }
A connection manager has become available. Clients can now connect to the server through
the connection manager.

@param connectionManagerName the connection manager that has become available.
xmppserver/src/main/java/org/jivesoftware/openfire/multiplex/ConnectionMultiplexerManager.java