Bugs: LCDS-548 - Two more issues: if argumentNames was not set, we did not hit the special
case for a single XML parameter. Secondly (and more importantly), if there was a single String
parameter and the content type was XML the String would get converted using the SimpleXMLEncoder
which escaped the string (and the request body would guaranteed to not be valid XML).
With this fix, a single String parameter is now fed in directly as the body of the HTTP
request when the content type is XML.
QA: yes, verify the bug is fixed
Doc: Could use a release note because of the behavioral change:
"There has been a minor behavior change to the HTTPService when you set
its contentType to 'application/xml'. If you call 'send' with a single String parameter
that value is now treated as the XML String itself and placed directly into the request
body. Previously the request body was formed by escaping all HTML control characters
found in the String."