Program: 89024
Project: 89024
Buggy source:
public static Result join(long id){
  Account account=Component.currentAccount();
  Group group=Group.findById(id);
  GroupAccount groupAccount;
  if (Secured.isMemberOfGroup(group,account)) {
    Logger.debug("String_Node_Str");
    flash("String_Node_Str","String_Node_Str");
    return redirect(controllers.routes.GroupController.view(id,PAGE));
  }
  groupAccount=GroupAccount.find(account,group);
  if (groupAccount != null && groupAccount.linkType.equals(LinkType.request)) {
    flash("String_Node_Str","String_Node_Str");
    return redirect(controllers.routes.GroupController.index());
  }
  if (groupAccount != null && groupAccount.linkType.equals(LinkType.reject)) {
    flash("String_Node_Str","String_Node_Str");
    return redirect(controllers.routes.GroupController.index());
  }
  if (groupAccount != null && groupAccount.linkType.equals(LinkType.invite)) {
    groupAccount.linkType=LinkType.establish;
    groupAccount.update();
    flash("String_Node_Str","String_Node_Str" + group.title + "String_Node_Str");
    return redirect(controllers.routes.GroupController.index());
  }
 else   if (group.groupType.equals(GroupType.open)) {
    groupAccount=new GroupAccount(account,group,LinkType.establish);
    groupAccount.create();
    flash("String_Node_Str","String_Node_Str" + group.title + "String_Node_Str");
    return redirect(controllers.routes.GroupController.view(id,PAGE));
  }
 else   if (group.groupType.equals(GroupType.close)) {
    groupAccount=new GroupAccount(account,group,LinkType.request);
    groupAccount.create();
    group.temporarySender=account;
    NotificationService.getInstance().createNotification(group,Group.GROUP_NEW_REQUEST);
    flash("String_Node_Str",Messages.get("String_Node_Str"));
    return redirect(controllers.routes.GroupController.index());
  }
 else   if (group.groupType.equals(GroupType.course)) {
    return redirect(controllers.routes.GroupController.token(id));
  }
  return redirect(controllers.routes.GroupController.index());
}

Fixed version (ground truth):
@Transactional public static Result join(long id){
  Account account=Component.currentAccount();
  Group group=Group.findById(id);
  GroupAccount groupAccount;
  if (Secured.isMemberOfGroup(group,account)) {
    Logger.debug("String_Node_Str");
    flash("String_Node_Str","String_Node_Str");
    return redirect(controllers.routes.GroupController.view(id,PAGE));
  }
  groupAccount=GroupAccount.find(account,group);
  if (groupAccount != null && groupAccount.linkType.equals(LinkType.request)) {
    flash("String_Node_Str","String_Node_Str");
    return redirect(controllers.routes.GroupController.index());
  }
  if (groupAccount != null && groupAccount.linkType.equals(LinkType.reject)) {
    flash("String_Node_Str","String_Node_Str");
    return redirect(controllers.routes.GroupController.index());
  }
  if (groupAccount != null && groupAccount.linkType.equals(LinkType.invite)) {
    groupAccount.linkType=LinkType.establish;
    groupAccount.update();
    flash("String_Node_Str","String_Node_Str" + group.title + "String_Node_Str");
    return redirect(controllers.routes.GroupController.index());
  }
 else   if (group.groupType.equals(GroupType.open)) {
    groupAccount=new GroupAccount(account,group,LinkType.establish);
    groupAccount.create();
    flash("String_Node_Str","String_Node_Str" + group.title + "String_Node_Str");
    return redirect(controllers.routes.GroupController.view(id,PAGE));
  }
 else   if (group.groupType.equals(GroupType.close)) {
    groupAccount=new GroupAccount(account,group,LinkType.request);
    groupAccount.create();
    group.temporarySender=account;
    NotificationService.getInstance().createNotification(group,Group.GROUP_NEW_REQUEST);
    flash("String_Node_Str",Messages.get("String_Node_Str"));
    return redirect(controllers.routes.GroupController.index());
  }
 else   if (group.groupType.equals(GroupType.course)) {
    return redirect(controllers.routes.GroupController.token(id));
  }
  return redirect(controllers.routes.GroupController.index());
}