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

*** 1,7 ****
  /*
!  * Copyright (c) 2015, 2016, 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
--- 1,7 ----
  /*
!  * 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
*** 58,63 ****
--- 58,81 ----
              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;
+     }
  }