Second sorting click on a column in 'Ensemble8 example TableView' and in other apps throws:

Exception in thread "JavaFX Application Thread" java.lang.ClassCastException: ensemble.samples.contr
ols.table.tableview.Person cannot be cast to java.lang.Comparable
        at com.sun.javafx.collections.SortHelper.mergeSort(SortHelper.java:213)
        at com.sun.javafx.collections.SortHelper.sort(SortHelper.java:80)
        at com.sun.javafx.collections.SortHelper.sort(SortHelper.java:63)
        at com.sun.javafx.collections.ObservableListWrapper.sort(ObservableListWrapper.java:215)
        at javafx.collections.FXCollections.sort(FXCollections.java:670)
        at javafx.scene.control.TableView$3.call(TableView.java:367)
        at javafx.scene.control.TableView$3.call(TableView.java:336)
        at javafx.scene.control.TableView.sort(TableView.java:1330)
        at javafx.scene.control.TableView.doSort(TableView.java:1360)
        at javafx.scene.control.TableView.access$100(TableView.java:259)
        at javafx.scene.control.TableView$4.onChanged(TableView.java:432)
        at com.sun.javafx.collections.ListListenerHelper$Generic.fireValueChangedEvent(ListListenerHelper.java:315)
        at com.sun.javafx.collections.ListListenerHelper.fireValueChangedEvent(ListListenerHelper.java:72)
        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.remove(ModifiableObservableListBase.java:183)
        at javafx.collections.ModifiableObservableListBase.remove(ModifiableObservableListBase.java:171)
        at com.sun.javafx.scene.control.skin.TableColumnHeader.sortColumn(TableColumnHeader.java:727)
        at com.sun.javafx.scene.control.skin.TableColumnHeader.access$600(TableColumnHeader.java:74)

        at com.sun.javafx.scene.control.skin.TableColumnHeader$7.handle(TableColumnHeader.java:248)
        at com.sun.javafx.scene.control.skin.TableColumnHeader$7.handle(TableColumnHeader.java:236)
        at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:86)
        at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238)
        at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191)
        at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59)
        at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
        at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
        at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
        at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
        at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
        at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
        at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
        at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
        at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
        at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
        at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
        at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
        at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
        at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:54)
        at javafx.event.Event.fireEvent(Event.java:203)
        at javafx.scene.Scene$MouseHandler.process(Scene.java:3591)
        at javafx.scene.Scene$MouseHandler.process(Scene.java:3385)
        at javafx.scene.Scene$MouseHandler.access$1900(Scene.java:3336)
        at javafx.scene.Scene.impl_processMouseEvent(Scene.java:1618)
        at javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:2395)
        at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:312)
        at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:237)
        at java.security.AccessController.doPrivileged(Native Method)
        at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:354)
        at com.sun.glass.ui.View.handleMouseEvent(View.java:514)
        at com.sun.glass.ui.View.notifyMouse(View.java:877)
        at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
        at com.sun.glass.ui.win.WinApplication.access$300(WinApplication.java:39)
        at com.sun.glass.ui.win.WinApplication$3$1.run(WinApplication.java:101)
        at java.lang.Thread.run(Thread.java:724)