How to persist session when passing to class/object

"I want to get the paths from a different class which processes the query"

Ok - i see what you are doing. I have never tired this - I have always developed QueryBuilder App Logic using  different methods in the same class - not different classes. 

You can try passing the QueryBuilder Object itself -- for example - 

Servlet Class{

@Reference
private QueryBuilder builder;

@Reference
private ServiceA serA;

@Reference
private ServiceB servB;

@Reference
private ServiceC servC;

doGet

{

serA.getPathA(builder); 

serB.getPathB(builder); 

serC.getPathC(builder); 

}

}

Assuming:

ServiceA - expose method getPathA(QueryBuilder qb)

ServiceB - expose method getPathB(QueryBuilder qb)

ServiceC - expose method getPathB(QueryBuilder qb)

I have never tried this. Since QueryBuilder is a managed object and was created with Dependency Injection, not sure if this will work in other classes or if you will have to re-create it in each service.

Try that and see what happens. I am also assuming that the other classes are also using @Service annotations.  

Like I mentioned - i also keep the QueryBuilder logic in the same class as it's defined as a data member of the class and can be used in many class methods without issue. 

Also since you need a session - you may have to re-create the session in each class as well:

builder.createQuery(PredicateGroup.create(map), session)