The client code has a "com.sun.awt.AWTUtilities" class which at some point(jdk6u10) in the past was used as a kind of "public" API.

In jdk9 this class is inaccessible and all its functionality was already provided by the public API, so this class can be removed.

AWTUtilities.isTranslucencySupported()/AWTUtilities.isWindowShapingSupported()
    -> GraphicsDevice.isWindowTranslucencySupported()

AWTUtilities.setWindowOpacity()/AWTUtilities.getWindowOpacity()
    -> Window.setOpacity/getOpacity

AWTUtilities.getWindowShape()/AWTUtilities.setWindowShape()
    -> Window.setShape()/getShape()

AWTUtilities.setWindowOpaque/AWTUtilities.isWindowOpaque
    -> setBackground()/isOpaque()

AWTUtilities.isTranslucencyCapable
    -> GraphicsConfiguration.isTranslucencyCapable()

AWTUtilities.setComponentMixingCutoutShape
    -> Component.setMixingCutoutShape()

CSR will be created after technical review.