@Override
    public String toString()
    {
        return "NettyServerConnectionHandler{" +
            "directTLS=" + directTLS +
            ", sslInitDone=" + sslInitDone +
            ", configuration=" + configuration +
            '}';
    }
Enable / disable backup delivery of stanzas to the XMPP server itself when a stanza failed to be delivered on a
server-to-server connection. When disabled, stanzas that can not be delivered on the connection are discarded.
xmppserver/src/main/java/org/jivesoftware/openfire/nio/NettyServerConnectionHandler.java