8260592: jpackage tests fail when Desktop is not supported

Reviewed-by: asemenyuk, herrick

Author: shipilev

test/jdk/tools/jpackage/apps/image/Hello.java

@@ -154,6 +154,12 @@ private static Hello createInstance() {
 
         trace("Environment supports a display");
 
+        if (!Desktop.isDesktopSupported()) {
+            return null;
+        }
+
+        trace("Environment supports a desktop");
+
         try {
             // Disable JAB.
             // Needed to suppress error: