我有一個帶有字符串和 int 的簡單結構。當我解組 json 時，如果以小寫字符串開頭，則不會解析結構成員。即使我在同一個包中使用package mainimport (    "encoding/json"    "fmt")type Bird struct {  Species string  Description string  lifespan int}func main() {    birdJson := `{"species": "pigeon","description": "likes to perch on rocks","lifespan": 9}`    var bird Bird       json.Unmarshal([]byte(birdJson), &bird)    fmt.Printf("Species: %s, Description: %s,lifespan: %d", bird.Species, bird.Description,bird.lifespan)    //Cant read the lifespan ??}