How to use source: function()... and AJAX in JQuery UI autocomplete

I need a little bit help with JQuery UI Autocomplete. I want my textfield (.suggest-user) display names from an AJAX request. This is what I have:

jQuery("input.suggest-user").autocomplete({
    source : function(request, response) {
        var name = jQuery("input.suggest-user").val();
        jQuery.get("usernames.action?query=" + name, function(data) {
            console.log(data);  // Ok, I get the data. Data looks like that:
            test = data;        // ["one@abc.de", "onf@abc.de","ong@abc.de"]
            return test;        // But what now? How do I display my data?
        });
    },
    minLength : 3
});

Any help is very much appreciated.