public List<EmployeeVacationDuration> getEmployeeTotalVacationDurations()
	{
		TypedQuery<EmployeeVacationDuration> query = manager.createQuery("SELECT NEW com.jpa.demo.services.EmployeeVacationDuration(e, SUM(v.days)) FROM Employee e JOIN e.vacations v GROUP BY e", EmployeeVacationDuration.class);
		
		return query.getResultList();
	}