src/java.desktop/share/classes/sun/java2d/marlin/MarlinUtils.java

@@ -1,7 +1,7 @@
 /*
- * Copyright (c) 2015, 2016, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2015, 2018, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.  Oracle designates this

@@ -58,6 +58,24 @@
             System.out.print("WARNING: ");
             System.out.println(msg);
             th.printStackTrace(System.err);
         }
     }
+
+    // From sun.awt.util.ThreadGroupUtils
+
+    /**
+     * Returns a root thread group.
+     * Should be called with {@link sun.security.util.SecurityConstants#MODIFY_THREADGROUP_PERMISSION}
+     *
+     * @return a root {@code ThreadGroup}
+     */
+    public static ThreadGroup getRootThreadGroup() {
+        ThreadGroup currentTG = Thread.currentThread().getThreadGroup();
+        ThreadGroup parentTG = currentTG.getParent();
+        while (parentTG != null) {
+            currentTG = parentTG;
+            parentTG = currentTG.getParent();
+        }
+        return currentTG;
+    }
 }