8159374: Taskbar.setIconBadge() spec omits mention of exception for ICON_BADGE_TEXT feature

Reviewed-by: alexsch, ssadetsky

jdk/src/java.desktop/share/classes/java/awt/Taskbar.java

@@ -364,7 +364,8 @@ public class Taskbar {
      * @throws SecurityException if a security manager exists and it denies the
      * {@code AWTPermission("showWindowWithoutWarningBanner")} permission.
      * @throws UnsupportedOperationException if the current platform
-     * does not support the {@link Taskbar.Feature#ICON_BADGE_NUMBER} feature
+     * does not support the {@link Taskbar.Feature#ICON_BADGE_NUMBER}
+     * or {@link Taskbar.Feature#ICON_BADGE_TEXT} feature
      */
     public void setIconBadge(final String badge) {
         checkAWTPermission();

jdk/src/java.desktop/unix/classes/sun/awt/X11/XTaskbarPeer.java

@@ -107,6 +107,8 @@ final class XTaskbarPeer implements TaskbarPeer {
                 val = Long.parseLong(badge);
                 visible = true;
             } catch (NumberFormatException e) {
+                throw new UnsupportedOperationException("The " + Feature.ICON_BADGE_TEXT
+                    + " feature is not supported on the current platform!");
             }
         }
         setBadge(val, visible);