Displaying PUT body format with go-restful and swagger

I am using go-restful and swagger to generate apidocs which is working great. The problem I am facing is that when I add a body parameter to the documentation I would like to specify the DataType and its format. I can specify the DataType (i.e. UserFields), but the format of the JSON does not show in the Swagger UI, which can be very convenient.

Here is an example of what I am talking about:
The following link shows a body parameter and the corresponding JSON/model next to it http://petstore.swagger.wordnik.com/#!/store/placeOrder

In my case, the JSON/model is missing and only the DataType is displayed http://ibounce.co:8282/apidocs/#!/users/PutUserField

Here is the sample Go code is generates the documentation for this specific endpoint.

ws.Route(ws.PUT("/{id}/fields").
    To(PutUserField).
	Doc("Update user fields").
	Operation("PutUserField").
	Param(ws.HeaderParameter("Authorization", "username and password").DataType("string")).
	Param(ws.PathParameter("id", "identifier of the user").DataType("int")).
	Param(ws.BodyParameter("body", "identifier of the user").DataType("UserFields")).
	Returns(http.StatusOK, http.StatusText(http.StatusOK), User{}).
	Returns(http.StatusUnauthorized, http.StatusText(http.StatusUnauthorized), ApiError{}).
	Returns(http.StatusBadRequest, http.StatusText(http.StatusBadRequest), ApiError{}))

UserFields is a struct:

type UserFields struct {
   Email   	string `json:"email,omitempty"`
   Phone  		string `json:"phone,omitempty"`
   URL  		string `json:"url,omitempty"`
   Address  	string `json:"address,omitempty"`
}

Any suggestions will be appreciated.

I figured it out. In the Go code above instead of

DataType("UserFields")

I have to use

DataType("main.UserFields")