RFR 8206915: XDH TCK issues

[Adam Petcher]

A couple of conformance issues were found during TCK development for 
XDH. Both required very small modifications to fix, so I put them under 
the same ticket/review in order to save time. The actual information 
about the issues can be found in the sub-tasks of the ticket.

This fix needs to go into JDK 11, so I'm hoping a Reviewer can take a 
look at this soon.

JBS: https://bugs.openjdk.java.net/browse/JDK-8206915
Webrev: http://cr.openjdk.java.net/~apetcher/8206915/webrev.00/