The following "quasi-public" methods were added in JavaFX 2.0 to support rendering to an image (snapshot) and conversion to / from a BufferedImage before public API was available:
Scene:
renderToImage(Object)
renderToImage(Object,float)
Image:
impl_toExternalImage(Object)
impl_fromExternalImage(Object)
impl_isExternalFormatSupported(Class)
In JavaFX 2.2 we added public API to support these needs, but left the unsupported methods to allow the internal users (primarily scene builder and JDeveloper) time to migrate. In FX 8 we need to remove these methods.