Grails left outer join between unrelated domains.(one way one to many relationship)

Question

I am following this link to bring some positive changes regarding performance in my app.

I have following two classes

class Topic {

    String title
    String body
    String type
    User user

    static mapping = {
        body type:"text"
    }
}

and

class Follower {
    Topic topic
    User user
    static constraints = {
    }
}

Keeping above two classes in mind, is it possible to write equivalent criteria for following query?

SELECT title,follower.user_ID,topic.id  FROM TOPIC 
left outer join follower on topic.id = follower.topic_id
where follower.user_id = 1 or follower.user_id is null;

I came up with following criteria which fails because there is neither reference of follower in topic nor I could find a way to swing this criteria to right join because there is no such criteria specification

def recentQuestions = Topic.createCriteria().list([sort:'lastUpdated',order:'desc',max:5]){
            createAlias  "follower", "f" , CriteriaSpecification.LEFT_JOIN

            or{
                eq('f.user',u)
                isNull('f.user')
            } 
            eq('type','FORUM',[ignoreCase: true])

        }