public function getFullName($first = NULL, $middle = NULL, $last = NULL) {

        $user_first_name = $this->getPropertyValue("user_first_name");
        $user_middle_name = $this->getPropertyValue("user_middle_name");
        $user_last_name = $this->getPropertyValue("user_last_name");
        $user_full_name = implode(' ', array(empty($user_first_name) ? $first : $user_first_name, empty($user_middle_name) ? $middle : $user_middle_name, empty($user_last_name) ? $last : $user_last_name));

        if (!empty($user_full_name)) {
            return $user_full_name;
        }
    }