java.lang.IllegalArgumentException: object is not an instance of declaring class
        at sun.reflect.NativeMethodAccessorImpl.invoke0(NativeMethodAccessorImpl.java:0)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:597)
        at org.netbeans.modules.form.RADProperty.getTargetValue(RADProperty.java:111)
        at org.netbeans.modules.form.FormProperty.checkCurrentValue(FormProperty.java:995)
        at org.netbeans.modules.form.FormProperty.getValue(FormProperty.java:264)
        at org.openide.explorer.propertysheet.PropUtils.updateEdFromProp(PropUtils.java:882)
        at org.openide.explorer.propertysheet.PropUtils.getPropertyEditor(PropUtils.java:855)
        at org.openide.explorer.propertysheet.PropUtils.getPropertyEditor(PropUtils.java:795)
        at org.openide.explorer.propertysheet.SheetTable.onCustomEditorButton(SheetTable.java:840)
        at org.openide.explorer.propertysheet.SheetTable.processMouseEvent(SheetTable.java:703)
        at java.awt.Component.processEvent(Component.java:6028)
        at java.awt.Container.processEvent(Container.java:2041)
        at java.awt.Component.dispatchEventImpl(Component.java:4630)
        at java.awt.Container.dispatchEventImpl(Container.java:2099)
        at java.awt.Component.dispatchEvent(Component.java:4460)
        at java.awt.LightweightDispatcher.retargetMouseEvent(LightweightDispatcher.java:4574)
        at java.awt.LightweightDispatcher.processMouseEvent(LightweightDispatcher.java:4235)
        at java.awt.LightweightDispatcher.dispatchEvent(LightweightDispatcher.java:4168)
        at java.awt.Container.dispatchEventImpl(Container.java:2085)
        at java.awt.Window.dispatchEventImpl(Window.java:2475)
        at java.awt.Component.dispatchEvent(Component.java:4460)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:599)
        at org.netbeans.core.TimableEventQueue.dispatchEvent(TimableEventQueue.java:104)
        at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269)
        at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)