public GroupsInKafedra(List <Gruppa> groups, Kafedra kafedra)
 {
     this.groups  = groups;
     this.kafedra = kafedra;
 }
 public TeachersInKafedraView(Kafedra kafedra, List <Teacher> teachers)
 {
     this.teachers = teachers;
     this.kafedra  = kafedra;
 }