<AWT Dev> <AWT dev>[9] Review request for 8016313: java.awt.Headless exception has no spec since its creation

[Semyon Sadetsky]

Hello,

Please review fix for JDK9:

bug: https://bugs.openjdk.java.net/browse/JDK-8016313

webrev: http://cr.openjdk.java.net/~ssadetsky/8016313/webrev.00/

HeadlessException was poorly specified. The improved javadocs are added 
to the class.

--Semyon