The API docs are generated by javafxdoc as part of running the "ant sdk" target.

When running the following @example program, which is in javafx.scene.Scene, an exception occurs, and no example image is produced. The javafxdoc tool renders @example programs using the "renderToScene" method via reflection.

The following program:

@example
import javafx.scene.*;
import javafx.scene.paint.*;
import javafx.scene.shape.*;

Scene {
    width: 250
    height: 150
    fill: LinearGradient {
        endX: 0.0
        stops: [ Stop { offset: 0.0 color: Color.LIGHTGRAY }
                 Stop { offset: 1.0 color: Color.GRAY } ]
    }
    content: [
        Circle { centerX: 40 centerY: 50 radius: 25 fill: Color.GREEN }
        Rectangle { x: 100 y: 25 width: 75 height: 50 fill: Color.BLUE }
    ]
}
@endexample

generates the following exception:

java.lang.UnsupportedOperationException: ProportionalPaint is not designed to be used directly by rendering operations
    at com.sun.javafx.tk.swing.Gradients$ProportionalGradientDelegate.createContext(Gradients.java:118)

Here is the full stack trace (or at least as much of it as is printed):

     [java] java.lang.reflect.InvocationTargetException
     [java] at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
     [java] at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
     [java] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
     [java] at java.lang.reflect.Method.invoke(Method.java:597)
     [java] at com.sun.tools.xslhtml.XHTMLProcessingUtils.renderScriptToImage(XHTMLProcessingUtils.java:706)
     [java] at com.sun.tools.xslhtml.XHTMLProcessingUtils.access$200(XHTMLProcessingUtils.java:92)
     [java] at com.sun.tools.xslhtml.XHTMLProcessingUtils$4.run(XHTMLProcessingUtils.java:637)
     [java] at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:199)
     [java] at java.awt.EventQueue.dispatchEvent(EventQueue.java:597)
     [java] at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269)
     [java] at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184)
     [java] at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174)
     [java] at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169)
     [java] at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161)
     [java] at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)
     [java] Caused by: java.lang.UnsupportedOperationException: ProportionalPaint is not designed to be used directly by rendering operations
     [java] at com.sun.javafx.tk.swing.Gradients$ProportionalGradientDelegate.createContext(Gradients.java:118)
     [java] at sun.java2d.pipe.AlphaPaintPipe.startSequence(AlphaPaintPipe.java:65)
     [java] at sun.java2d.pipe.SpanShapeRenderer$Composite.startSequence(SpanShapeRenderer.java:38)
     [java] at sun.java2d.pipe.SpanShapeRenderer.renderRect(SpanShapeRenderer.java:143)
     [java] at sun.java2d.pipe.SpanShapeRenderer.fill(SpanShapeRenderer.java:87)
     [java] at sun.java2d.pipe.PixelToShapeConverter.fillRect(PixelToShapeConverter.java:44)
     [java] at sun.java2d.pipe.ValidatePipe.fillRect(ValidatePipe.java:58)
     [java] at sun.java2d.SunGraphics2D.fillRect(SunGraphics2D.java:2265)
     [java] at com.sun.javafx.tk.swing.SwingScene.renderToImage(SwingScene.java:184)
     [java] at javafx.scene.Scene.renderToImage(Scene.fx:228)
     [java] at javafx.scene.Scene.renderToImage(Scene.fx:210)
     [java] ... 15 more

Note that due to JFXC-3421 the error message is lost. If you apply the patch from the webrev in that bug report, then you will see the error message when doing a full foreset build of the SDK.