No Such Method error running SpringAnimation sample: com.sun.awt.AWTUtilities.setWindowOpacity(java.awt.Window, float)

Here is the output of running SpringAnimation on the current scrum/build forest, with the command:
     ......./artifacts/sdk/bin/javafx -classpath SpringAnimation.jar custominterpolator.SpringDemo

width = 0.0 0.0
width = 186.15625 124.53125
width = 186.15625 124.53125
Error setting window opacity using AWTUtilities
java.lang.NoSuchMethodException: com.sun.awt.AWTUtilities.setWindowOpacity(java.awt.Window, float)
at java.lang.Class.getMethod(Class.java:1619)
at com.sun.javafx.tk.swing.WindowImpl.setWindowOpacity(WindowImpl.java:227)
at com.sun.javafx.tk.swing.WindowStage.setOpacity(WindowStage.java:314)
at javafx.stage.Stage$12.onChange(Stage.fx:313)
at com.sun.javafx.runtime.location.FloatVariable$3.onAction(FloatVariable.java:158)
at com.sun.javafx.runtime.location.FloatVariable$3.onAction(FloatVariable.java:155)
at com.sun.javafx.runtime.location.DependencyIterator.action(AbstractLocation.java:539)
at com.sun.javafx.runtime.location.DependencyIterator.action(AbstractLocation.java:527)
at com.sun.javafx.runtime.util.Linkables.iterate(Linkables.java:82)
at com.sun.javafx.runtime.location.AbstractLocation.iterateChildren(AbstractLocation.java:282)
at com.sun.javafx.runtime.location.FloatVariable.notifyListeners(FloatVariable.java:155)
at com.sun.javafx.runtime.location.FloatVariable.replaceValue(FloatVariable.java:94)
at com.sun.javafx.runtime.location.FloatVariable.setAsFloat(FloatVariable.java:113)
at javafx.stage.Stage.applyDefaults$opacity(Stage.fx:312)
at javafx.stage.Stage.initialize$(Stage.fx:312)
at custominterpolator.SpringDemo.javafx$run$(SpringDemo.fx:176)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:623)
at com.sun.javafx.runtime.provider.GUIRuntimeProvider$1.run(GUIRuntimeProvider.java:66)
at com.sun.javafx.tk.swing.SwingToolkit$StartupRoutine.run$impl(SwingToolkit.fx:754)
at com.sun.javafx.tk.swing.SwingToolkit$StartupRoutine.run(SwingToolkit.fx:707)
at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:235)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:603)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:286)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:201)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:191)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:186)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:178)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:139)
width = 228.0 286.0