Mengapa medan struct Go saya kosong semasa menghuraikan JSON?

// Define your struct with exported fields
type Settings struct {
    ServerMode bool `json:"serverMode"`
    SourceDir  string `json:"sourceDir"`
    TargetDir  string `json:"targetDir"`
}

func main() {
    // Open the config file
    configFile, err := os.Open("config.json")
    if err != nil {
        printError("opening config file", err.Error())
    }

    jsonParser := json.NewDecoder(configFile)
    settings := Settings{} // Initialize the struct

    // Decode the JSON
    if err = jsonParser.Decode(&settings); err != nil {
        printError("parsing config file", err.Error())
    }

    fmt.Printf("%v %s %s", settings.ServerMode, settings.SourceDir, settings.TargetDir)
}