public Duration getMaxIdleTime() {
        return ConnectionSettings.Server.IDLE_TIMEOUT_PROPERTY.getValue();
    }
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