Program: 188210
Project: 188210
Buggy source:
@Override protected void configureDisplay(CellTable<Notification> display){
  fromUser=new TextColumn<Notification>(){
    @Override public String getValue(    Notification notification){
      return notification != null ? notification.getFromUser() : null;
    }
  }
;
  recipientUsers=new TextColumn<Notification>(){
    @Override public String getValue(    Notification notification){
      return notification != null ? StringUtils.prettyPrint(notification.getRecipientUsers()) : null;
    }
  }
;
  sentOn=new Column<Notification,Date>(new DateCell(DateTimeFormat.getFormat(PredefinedFormat.DATE_TIME_MEDIUM))){
    @Override public Date getValue(    Notification notification){
      return notification != null ? notification.getSentOn() : null;
    }
  }
;
  subject=new TextColumn<Notification>(){
    @Override public String getValue(    Notification notification){
      return notification != null ? notification.getSubject() : null;
    }
  }
;
  acknowledged=new Column<Notification,SafeHtml>(new SafeHtmlCell()){
    @Override public SafeHtml getValue(    Notification notification){
      SafeHtml ret=null;
      if (notification != null) {
        if (notification.isAcknowledged()) {
          ret=SafeHtmlUtils.fromSafeConstant("String_Node_Str" + messages.showMessageAcknowledged() + "String_Node_Str");
        }
 else {
          ret=SafeHtmlUtils.fromSafeConstant("String_Node_Str" + messages.showMessageNotAcknowledged() + "String_Node_Str");
        }
      }
      return ret;
    }
  }
;
  state=new Column<Notification,SafeHtml>(new SafeHtmlCell()){
    @Override public SafeHtml getValue(    Notification notification){
      SafeHtml ret=null;
      if (notification != null) {
        ret=HtmlSnippetUtils.getNotificationStateHTML(notification.getState());
      }
      return ret;
    }
  }
;
  fromUser.setSortable(true);
  sentOn.setSortable(true);
  subject.setSortable(true);
  acknowledged.setSortable(true);
  state.setSortable(true);
  addColumn(fromUser,messages.notificationFrom(),true,false);
  addColumn(recipientUsers,messages.notificationTo(),true,false);
  addColumn(sentOn,messages.notificationSentOn(),true,false,13);
  addColumn(subject,messages.notificationSubject(),true,false);
  addColumn(state,messages.notificationState(),true,false,7);
  addColumn(acknowledged,messages.notificationAck(),true,false,7);
  display.getColumnSortList().push(new ColumnSortInfo(sentOn,false));
  addStyleName("String_Node_Str");
}

Fixed version (ground truth):
@Override protected void configureDisplay(CellTable<Notification> display){
  fromUser=new TextColumn<Notification>(){
    @Override public String getValue(    Notification notification){
      return notification != null ? notification.getFromUser() : null;
    }
  }
;
  recipientUsers=new TextColumn<Notification>(){
    @Override public String getValue(    Notification notification){
      return notification != null ? StringUtils.prettyPrint(notification.getRecipientUsers()) : null;
    }
  }
;
  sentOn=new Column<Notification,Date>(new DateCell(DateTimeFormat.getFormat(RodaConstants.DEFAULT_DATETIME_FORMAT))){
    @Override public Date getValue(    Notification notification){
      return notification != null ? notification.getSentOn() : null;
    }
  }
;
  subject=new TextColumn<Notification>(){
    @Override public String getValue(    Notification notification){
      return notification != null ? notification.getSubject() : null;
    }
  }
;
  acknowledged=new Column<Notification,SafeHtml>(new SafeHtmlCell()){
    @Override public SafeHtml getValue(    Notification notification){
      SafeHtml ret=null;
      if (notification != null) {
        if (notification.isAcknowledged()) {
          ret=SafeHtmlUtils.fromSafeConstant("String_Node_Str" + messages.showMessageAcknowledged() + "String_Node_Str");
        }
 else {
          ret=SafeHtmlUtils.fromSafeConstant("String_Node_Str" + messages.showMessageNotAcknowledged() + "String_Node_Str");
        }
      }
      return ret;
    }
  }
;
  state=new Column<Notification,SafeHtml>(new SafeHtmlCell()){
    @Override public SafeHtml getValue(    Notification notification){
      SafeHtml ret=null;
      if (notification != null) {
        ret=HtmlSnippetUtils.getNotificationStateHTML(notification.getState());
      }
      return ret;
    }
  }
;
  fromUser.setSortable(true);
  sentOn.setSortable(true);
  subject.setSortable(true);
  acknowledged.setSortable(true);
  state.setSortable(true);
  addColumn(fromUser,messages.notificationFrom(),true,false);
  addColumn(recipientUsers,messages.notificationTo(),true,false);
  addColumn(sentOn,messages.notificationSentOn(),true,false,13);
  addColumn(subject,messages.notificationSubject(),true,false);
  addColumn(state,messages.notificationState(),true,false,7);
  addColumn(acknowledged,messages.notificationAck(),true,false,7);
  display.getColumnSortList().push(new ColumnSortInfo(sentOn,false));
  addStyleName("String_Node_Str");
}