RFR(XS): 8240142: Fix copyright in ThreadGroupReferenceImpl.h

[Chris Plummer]

Hello,

Please review the following copyright fix. A comma is missing:

https://bugs.openjdk.java.net/browse/JDK-8240142

diff --git 
a/src/jdk.jdwp.agent/share/native/libjdwp/ThreadGroupReferenceImpl.h 
b/src/jdk.jdwp.agent/share/native/libjdwp/ThreadGroupReferenceImpl.h
--- a/src/jdk.jdwp.agent/share/native/libjdwp/ThreadGroupReferenceImpl.h
+++ b/src/jdk.jdwp.agent/share/native/libjdwp/ThreadGroupReferenceImpl.h
@@ -1,5 +1,5 @@
  /*
- * Copyright (c) 1998, 2020 Oracle and/or its affiliates. All rights 
reserved.
+ * Copyright (c) 1998, 2020, 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

thanks,

Chris