RESTHandler - warnings

SmartGWT 5.0p

I see the following when accessing my RESTHandler servlet:

WARN [com.isomorphic.servlet.RequestContext]...Content type has already been set to text/html; charset=UTF-8 - setting to application/json

We define the servlet with:

defaultDataFormat = json
dynamicDataFormatParamName = theDataFormat
wrapJSONResponses = false

The calls are successful, but is there any way to fix these warnings?