I've found the solution. Maybe this answer would helpful for somebody.
Main idea is to apply monkeyPatchAutocomplete patch:
monkeyPatchAutocomplete();
function monkeyPatchAutocomplete()
{
$.ui.autocomplete.prototype._renderItem = function(ul, item) {
var regexp = new RegExp(this.term);
var highlightedVal = item.label.replace(regexp, "<span style='font-weight:bold;color:Blue;'>" + this.term + "</span>");
return $("<li'></li>")
.data("item.autocomplete", item)
.append("<a><img class='autocompleteUserAvatar' src='" + item.icon + "' />" + highlightedVal + "</a>")
.appendTo(ul);
};
}
var users;
$("#searchForUsersAutocomplete").tagit({
allowDuplicates: false,
removeConfirmation: true,
tagSource: function(search, showChoices) {
findUsers(search.term, function(jsonFoundUsers, status)//ajax-call to an externall server API
{
users = new Array();
for (var i = 0; i < jsonFoundUsers.users.length; i++)
{
var user =
{
value: jsonFoundUsers.users[i].username,
label: jsonFoundUsers.users[i].username,
icon: jsonFoundUsers.users[i].avatarUrl
};
users.push(user);
}
showChoices(users);
});
}
});