Various improvements

src/main/java/nl/connectedit/swiss/service/TournamentDivideService.java

@@ -64,6 +64,7 @@ public class TournamentDivideService {
       event.getGroups().add(group);
     } else {
       var groups = getGroups(registrations, event.getType());
+      groups.forEach(group -> group.setEvent(event));
       event.getGroups().addAll(groups);
     }
   }
@@ -146,7 +147,7 @@ nextRegistration:
     var team = new Team();
     team.setPlayer1(registration.getPlayer());
     team.setPlayer2(registration.getPartner());
-    team.setGroup(group);
+    team.setGroups(List.of(group));
 
     return team;
   }