public class Reservation implements Serializable
{
   private Long code;
   private TravelFileHeader travelFileHeader;
   private String fileName;
   private Calendar creationDate;
   private Calendar startDate;
   private Calendar endDate;
   private Reservation controlReservation;
   private Reservation replacesReservation;
   private Reservation isReplacedByReservation;
   private boolean isOnRequest;
   private Service service;
   private ParsysUser parsysUser;
   private String confirmationStatus;
   private BranchOffice branchOffice;
   private String reservationType;
   
   private Set comments;
//getters and setters follows...
}

List rsList = HibernateSession.currentSession().createQuery("from Reservation as res where res.travelFileHeader.code = " + travelFile.getCode().longValue() + " and res.isReplacedByReservation = null").list();