### Websphere and Jackson ###
I'm filing this under **I hope someone finds this in a google search to avoid the pain I just went through**.

Websphere 7+ includes Jackson in it's global library (which gets loaded first).
This must be a very old version of Jackson, because ObjectMapper is missing it's writer method.

Work arounds depend on your situation.
I wasn't in control of the server so I used json.org in place of Jackson, but ideally you would want a isolated shared library.