[10] RFR: 8161973: PKIXRevocationChecker.getSoftFailExceptions() not working

[Sean Mullan]

Please review this fix to the getSoftFailExceptions method of 
PKIXRevocationChecker so that it does not always return an empty List. 
The problem was that the clone method of the PKIXRevocationChecker 
implementation was creating a new List each time it was called, and the 
Exceptions were not being added to the original List that is returned by 
getSoftFailException. The fix is to not override clone and make a copy 
of the List. This is still safe because the caller cannot modify its 
contents (the List returned by getSoftFailExceptions is unmodifiable).

http://cr.openjdk.java.net/~mullan/webrevs/8161973/webrev.00/
--Sean