QueryDsl - issue with mapping query with case builder inside aggregates - sql

Question

I have a problem constructing a query which uses cases inside aggregates.
My setup: QueryDsl 3.3.2, JPA + Hibernate 3.6.10.Final
I Have two entities (psudo code):
Car {
private String ownerNumber;
private String color;
}
Client {
private String number;
}
There is no direct relationship between those two, just for some reporting simplicity Car holds Client number reference.
The first problem:
As I found on different SO posts I cannot use join on this etities using custom properties, I need to use for example cross join. Using: from client cl, car.c where cl.number=c.owner_number - the drawback is I'm not able to get all clients (which indicates lack of a car) - just thos that have connection for those two props. This is not too good for my reports but let's say I can live with that.
The second problem:
In the same query I also need to aggregate some data - I need to count all user cars, and let say all red. So I need sth like this:
SELECT c.number, count(c.id) AS total, SUM(CASE WHEN c.color='RED' THEN 1 ELSE 0 END) as allRed FROM client cl, car c WHERE cl.number=c.ownerNumber GROUP BY c.number;
This query works as expected;
For QueryDsl I have:
QClient client = Qclient.client;
QCar car = Qcar.car;
NumberExpression<Integer> redCarExp = new CaseBuilder()
.when(car.color.eq("RED"))
.then(1)
.otherwise(0);
List<Tuple> list = new JPAQuery(em)
.from(client, car)
.where(client.number.eq(car.ownerNumber))
.groupBy(client.number)
.list(client.number, car.id.count(), redCarExp.sum());
Running this generates JPAQuery shown below and exception. Without the last sum() part all works ok. I'm not sure where is the issue here.
java.lang.ClassCastException: org.hibernate.hql.ast.tree.ParameterNode cannot be cast to org.hibernate.hql.ast.tree.SelectExpression
org.hibernate.hql.ast.tree.CaseNode.getFirstThenNode(CaseNode.java:44)
org.hibernate.hql.ast.tree.CaseNode.getDataType(CaseNode.java:40)
org.hibernate.hql.ast.util.SessionFactoryHelper.findFunctionReturnType(SessionFactoryHelper.java:402)
org.hibernate.hql.ast.tree.AggregateNode.getDataType(AggregateNode.java:82)
org.hibernate.hql.ast.tree.SelectClause.initializeExplicitSelectClause(SelectClause.java:154)
org.hibernate.hql.ast.HqlSqlWalker.useSelectClause(HqlSqlWalker.java:857)
org.hibernate.hql.ast.HqlSqlWalker.processQuery(HqlSqlWalker.java:645)
org.hibernate.hql.antlr.HqlSqlBaseWalker.query(HqlSqlBaseWalker.java:685)
org.hibernate.hql.antlr.HqlSqlBaseWalker.selectStatement(HqlSqlBaseWalker.java:301)
org.hibernate.hql.antlr.HqlSqlBaseWalker.statement(HqlSqlBaseWalker.java:244)
org.hibernate.hql.ast.QueryTranslatorImpl.analyze(QueryTranslatorImpl.java:256)
org.hibernate.hql.ast.QueryTranslatorImpl.doCompile(QueryTranslatorImpl.java:187)
org.hibernate.hql.ast.QueryTranslatorImpl.compile(QueryTranslatorImpl.java:138)
org.hibernate.engine.query.HQLQueryPlan.(HQLQueryPlan.java:101)
org.hibernate.engine.query.HQLQueryPlan.(HQLQueryPlan.java:80)
org.hibernate.engine.query.QueryPlanCache.getHQLQueryPlan(QueryPlanCache.java:124)
org.hibernate.impl.AbstractSessionImpl.getHQLQueryPlan(AbstractSessionImpl.java:156)
org.hibernate.impl.AbstractSessionImpl.createQuery(AbstractSessionImpl.java:135)
org.hibernate.impl.SessionImpl.createQuery(SessionImpl.java:1770)
org.hibernate.ejb.AbstractEntityManagerImpl.createQuery(AbstractEntityManagerImpl.java:277)
sun.reflect.GeneratedMethodAccessor74.invoke(Unknown Source)
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
java.lang.reflect.Method.invoke(Method.java:606)
org.springframework.orm.jpa.ExtendedEntityManagerCreator$ExtendedEntityManagerInvocationHandler.invoke(ExtendedEntityManagerCreator.java:342)
com.sun.proxy.$Proxy63.createQuery(Unknown Source)
sun.reflect.GeneratedMethodAccessor74.invoke(Unknown Source)
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
java.lang.reflect.Method.invoke(Method.java:606)
org.springframework.orm.jpa.SharedEntityManagerCreator$SharedEntityManagerInvocationHandler.invoke(SharedEntityManagerCreator.java:262)
com.sun.proxy.$Proxy63.createQuery(Unknown Source)
com.mysema.query.jpa.impl.AbstractJPAQuery.createQuery(AbstractJPAQuery.java:129)
com.mysema.query.jpa.impl.AbstractJPAQuery.createQuery(AbstractJPAQuery.java:97)
com.mysema.query.jpa.impl.AbstractJPAQuery.list(AbstractJPAQuery.java:242)
com.mysema.query.jpa.impl.AbstractJPAQuery.list(AbstractJPAQuery.java:236)