     {
     var statusCode: Int
     var headers = [String:String]()
-    var body: Data?
+    var body: HTTPBodyConvertible?
 
     func send(to client: URLProtocolClient, for sender: URLProtocol, url: URL)
         {

        return self
        }

    func withBody(_ string: String) -> Self
        { withBody(string.data(using: .utf8)!) }

    func withBody(_ data: Data) -> Self
        {
        stub.matcher.body = data
        return self

        return self
        }

    func withBody(_ data: HTTPBodyConvertible?) -> Self
        {
        var response = stub.response as! HTTPResponse
        response.body = data
