ValueResultConverterOfT.cs

public class ValueResultConverter<T> : IActionResultConverter
{
    public HttpResponseMessage Convert(HttpControllerContext controllerContext, object actionResult)
    {
        if (controllerContext == null)
        {
            throw Error.ArgumentNull("controllerContext");
        }

        HttpResponseMessage resultAsResponse = actionResult as HttpResponseMessage;
        if (resultAsResponse != null)
        {
            resultAsResponse.EnsureResponseHasRequest(controllerContext.Request);
            return resultAsResponse;
        }

        T value = (T)actionResult;
        return controllerContext.Request.CreateResponse<T>(HttpStatusCode.OK, value, controllerContext.Configuration);
    }
}