Openfire Proxy Authenticated - System Properties - update.proxy.host

Dears, I’ve set update.proxy.host and update.proxy.port in System Properties, but our Squid only works with username and password (authenticated). I had tried create update.proxy.username and update.proxy.password (encrypted), but I think it didn’t work. How can I solve it? What is the correct property name to username and password (update.proxy.??? )? Thank you.