json解组不起作用,但解码起作用

package conf

import (
    "os"
    "io/ioutil"
    "encoding/json"
)

type Configuration struct {
    Agents []Agent `json:"agents"`
    IbmWmqFolder string `json:"ibmWmqFolder"`
}

type Agent struct {
    AgentName string `json:"agentName"`
    Folders []string `json:"folders"`
}

func LoadConfiguration() (configuration Configuration) {
    jsonFile, err := os.Open("config.json")
    if err != nil {
        panic(err)
    }
    defer jsonFile.Close()
    byteValue, _ := ioutil.ReadAll(jsonFile)
    json.Unmarshal(byteValue, configuration)
    return
}

但如果我也这么做,但不是最后两行 byteValue

jsonParser := json.NewDecoder(jsonFile)
jsonParser.Decode(&configuration)
return