I have found out the answer in jpa removing child from collection. as a result adding orphanRemoval=true solved the problem.

@Entity(name ="alarmnotify_email_conf") @Table(name = "alarmnotify_email_conf") public class AlarmnotifyEmailConfEntity implements Serializable {

@OneToMany(mappedBy = "alarmnotifyEmailConfRef",cascade=CascadeType.ALL ,orphanRemoval=true) private List alarmnotifyEmailEntityList;

}//end of Class