Exception after retaining sorting column of TableV

Question

I am trying to retain my JavaFx Tableview sorting order after data in the table is reloaded. I am following the below mentioned link. Javafx: Re-sorting a column in a TableView

TableView rooms;
        ...
        TableColumn sortcolumn = null;
        SortType st = null;
        if (rooms.getSortOrder().size()>0) {
            sortcolumn = (TableColumn) rooms.getSortOrder().get(0);
            st = sortcolumn.getSortType();
        }

Then, after you are done updating the data in the TableView, you must restore the lost sort-column state and perform a sort.

   if (sortcolumn!=null) {
        rooms.getSortOrder().add(sortcolumn);
        sortcolumn.setSortType(st);
        sortcolumn.setSortable(true); // This performs a sort
    }

Everything works fine...sorting order is retained but the console is showing an exception at "rooms.getSortOrder().add(sortcolumn);"

Exception in thread "JavaFX Application Thread" java.lang.IndexOutOfBoundsException
       at com.sun.javafx.scene.control.ReadOnlyUnbackedObservableList.subList(ReadOnlyUnbackedObservableList.java:136)
       at javafx.collections.ListChangeListener$Change.getAddedSubList(ListChangeListener.java:242)
       at javafx.scene.control.TreeTableView$TreeTableViewArrayListSelectionModel.handleSelectedCellsListChangeEvent(TreeTableView.java:3244)
       at javafx.scene.control.TreeTableView$TreeTableViewArrayListSelectionModel.access$2000(TreeTableView.java:2289)
       at javafx.scene.control.TreeTableView.sort(TreeTableView.java:1817)
       at javafx.scene.control.TreeTableView.doSort(TreeTableView.java:1855)
       at javafx.scene.control.TreeTableView.lambda$new$114(TreeTableView.java:383)
       at com.sun.javafx.collections.ListListenerHelper$Generic.fireValueChangedEvent(ListListenerHelper.java:329)
       at com.sun.javafx.collections.ListListenerHelper.fireValueChangedEvent(ListListenerHelper.java:73)
       at javafx.collections.ObservableListBase.fireChange(ObservableListBase.java:233)
       at javafx.collections.ListChangeBuilder.commit(ListChangeBuilder.java:482)
       at javafx.collections.ListChangeBuilder.endChange(ListChangeBuilder.java:541)
       at javafx.collections.ObservableListBase.endChange(ObservableListBase.java:205)
       at javafx.collections.ModifiableObservableListBase.add(ModifiableObservableListBase.java:155)
       at java.util.AbstractList.add(AbstractList.java:108)
       at com.honda.galc.client.qi.repairentry.RepairEntryController.loadInitialData(RepairEntryController.java:260)
       at com.honda.galc.client.qi.repairentry.RepairEntryController.markDefectAsActualProblem(RepairEntryController.java:529)
       at com.honda.galc.client.qi.repairentry.RepairEntryController.addRepairMethods(RepairEntryController.java:184)

Any idea why such exception is coming?