RFR 8199435 : Unsafe publication of java.util.Properties.map

[Brent Christian]

Hi,

In JDK 9, 8029891[1] refactored java.util.Properties to store its values 
in an internal ConcurrentHashMap, and removed synchronization from 
"reader" methods in order to avoid potential hangs/deadlocks during 
classloading.

Claes has noticed that there is the possibility of the new 'map' field 
being observed with its default value (null), before being set.

After looking at the JSR 133 FAQ[2], I agree with Claes that we should 
make 'map' a field final.

Please review my change to do this:

Webrev:
http://cr.openjdk.java.net/~bchristi/8199435/webrev/
Issue:
https://bugs.openjdk.java.net/browse/JDK-8199435

Thanks,
-Brent

1. https://bugs.openjdk.java.net/browse/JDK-8029891
2. https://www.cs.umd.edu/~pugh/java/memoryModel/jsr-133-faq.html#finalRight