Rest service xml input does not unwrap to IS document

I have used json as input for my rest services so far and it was fine.now when i try to use xml as input it does not urwrap to IS doc format unlike json.is there anything i am missing?

Sample here:

http://techcommunity.softwareag.com/pwiki/-/wiki/Main/Rest%20Using%20XML%20-%20Code%20sample%20to%20receive%20XML%20as%20input%20in%20the%20REST%20service