golang str转json的转义问题

package main

import "fmt"
import "encoding/json"
import "bytes"

type Track struct {
    XmlRequest string `json:"xmlRequest"`
}

func JSONMarshal(t interface{}) ([]byte, error) {
    buffer := &bytes.Buffer{}
    encoder := json.NewEncoder(buffer)
    encoder.SetEscapeHTML(false)
    err := encoder.Encode(t)
    return buffer.Bytes(), err
}

func main() {
    message := Track{}
    message.XmlRequest = "XML"
    fmt.Println("Before Marshal", message)
    messageJSON, _ := JSONMarshal(message)
    fmt.Println("After marshal", string(messageJSON))
}