REST DSL Jackson date needs to be serialised to to ISO8601 with Zulu time

Issue

• We are trying to get the REST DSL to respond with timestamps in Zulu time.
• We don't have access to source code.
• What we get

{
  "some_date": "2016-02-03T05:13:44.255+0000"
}

• What we want (date with zulu time:

{
  "some_date": "2016-02-03T05:13:44.255Z"
}

• Is there a way to get Jackson to format dates as we require?