Getting rid of brackets in response values taken from reques

For some reason brackets are appearing around the values I pull from the request and insert into the response.

How to get rid of these?

def starcode = mockRequest.getRequestHeaders().get("X-STAR-SenderNameCode")
requestContext.starcode = starcode

Source (request):
X-STAR-SenderNameCode: XX

Target (response):
<DestinationNameCode>[XX]</DestinationNameCode>

Thanks for any help,

Tony