A DESCRIPTION OF THE REQUEST :
This is already available on CGraphicsDevice to internally support Retina screens on Macs - http://hg.openjdk.java.net/jdk9/client/jdk/file/1089d8a8a6e1/src/java.desktop/macosx/classes/sun/awt/CGraphicsDevice.java and the getScaleFactor API.

I'm requesting to expose this as public API so that external developers can query for the presence of high-resolution screens and adjust their rendering accordingly

JUSTIFICATION :
See http://bulenkov.com/2013/06/23/retina-support-in-oracle-jdk-1-7/ for how IntelliJ is using reflection to query the GraphicsDevice object on Mac machines. That way now fails on JDK 9 early access:

java.lang.IllegalAccessException: class UIUtil$DetectRetinaKit cannot access class sun.awt.CGraphicsDevice (in module java.desktop) because module java.desktop does not export sun.awt to unnamed module @7a2858
at java.base/jdk.internal.reflect.Reflection.throwIllegalAccessException(Reflection.java:445)
at java.base/jdk.internal.reflect.Reflection.throwIllegalAccessException(Reflection.java:436)
at java.base/jdk.internal.reflect.Reflection.ensureMemberAccess(Reflection.java:112)
at java.base/java.lang.reflect.AccessibleObject.slowCheckMemberAccess(AccessibleObject.java:407)
at java.base/java.lang.reflect.AccessibleObject.checkAccess(AccessibleObject.java:399)
at java.base/java.lang.reflect.Method.invoke(Method.java:530)
at UIUtil$DetectRetinaKit.isOracleMacRetinaDevice(UIUtil.java:66)


EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
I'd like to have a public API to officially query the scale factor / hi DPI "presence" on a specific GraphicsDevice object.
ACTUAL -
There is no such public API available.

CUSTOMER SUBMITTED WORKAROUND :
Use reflection to access CGraphicsDevice. Works on JDK 8 but fails on JDK 9.