Previously, when the XML pretty printer attempted to pretty print
the content of a request or response it would output an error to
System.err if the content was not valid XML. While, benign, this
output was distracting.
This commit updates the XML pretty printer to suppress its output to
System.err by configuring it with an ErrorHandler and an ErrorListener
that swallow any errors of which they are notified.
Closes gh-153
75085477b6