B4J Question jFXtrasGaugesdemo has some error

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Can anyone told me what's matter is following,Thanks a lots.

Program started.
main._appstart (java line: 168)
java.lang.IllegalArgumentException: EventType "javafx.event.EventType@4c7470aa"with parent "EVENT" already exists
at javafx.event.EventType.register(EventType.java:186)
at javafx.event.EventType.<init>(EventType.java:128)
at javafx.event.EventType.<init>(EventType.java:83)
at jfxtras.labs.scene.control.gauge.GaugeModel$GaugeModelEvent.<init>(GaugeModel.java:760)
at jfxtras.labs.scene.control.gauge.GaugeModel.fireGaugeModelEvent(GaugeModel.java:159)
at jfxtras.labs.scene.control.gauge.GaugeModel.setThreshold(GaugeModel.java:333)
at jfxtras.labs.scene.control.gauge.Gauge.setThreshold(Gauge.java:633)
at anywheresoftware.b4j.agraham.jfxtrascontrols.BatteryWrapper$LcdWrapper.innerInitialize(BatteryWrapper.java:566)
at anywheresoftware.b4j.objects.NodeWrapper.Initialize(NodeWrapper.java:75)
at b4j.example.main._appstart(main.java:168)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at anywheresoftware.b4a.BA.raiseEvent2(BA.java:93)
at anywheresoftware.b4a.BA.raiseEvent(BA.java:84)
at b4j.example.main.start(main.java:36)
at com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$162(LauncherImpl.java:863)
at com.sun.javafx.application.PlatformImpl.lambda$runAndWait$175(PlatformImpl.java:326)
at com.sun.javafx.application.PlatformImpl.lambda$null$173(PlatformImpl.java:295)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.javafx.application.PlatformImpl.lambda$runLater$174(PlatformImpl.java:294)
at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)
at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at com.sun.glass.ui.win.WinApplication.lambda$null$148(WinApplication.java:191)
at java.lang.Thread.run(Thread.java:745)