8036568: Serial incompatibility in java.util.TreeMap.NavigableSubMap

Reviewed-by: smarks

src/share/classes/java/util/TreeMap.java

 /*
- * Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2014, 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
@@ -1338,6 +1338,7 @@ public class TreeMap<K,V>
      */
     abstract static class NavigableSubMap<K,V> extends AbstractMap<K,V>
         implements NavigableMap<K,V>, java.io.Serializable {
+        private static final long serialVersionUID = -2102997345730753016L;
         /**
          * The backing map.
          */