如何在Kotlin中创建正确的JSON类(对于fuel)

我有一个返回json的请求:

{
  "success": 0,
  "errors": {
    "phone": [
      "Incorrect phone number"
    ]
  }
}

我塞住了燃料,而不是改装科特林。所以,我的课程是:

data class RegistrationResponse(
    val success: Int,
    val errors: RegistrationErrorsResponse?) {

    class Deserializer : ResponseDeserializable<RegistrationResponse> {
        override fun deserialize(content: String): RegistrationResponse? =
            Gson().fromJson(content, RegistrationResponse::class.java)
    }
}

data class RegistrationErrorsResponse(val phone: List<String>?) {

    class Deserializer : ResponseDeserializable<RegistrationErrorsResponse> {
        override fun deserialize(content: String): RegistrationErrorsResponse? =
            Gson().fromJson(content, RegistrationErrorsResponse::class.java)
    }
}

请求如下:

class Api {

    init {
        FuelManager.instance.basePath = SERVER_URL
    }

    fun registration(name: String, phone: String): Request =
        "/registration/"
            .httpPost(listOf("name" to name, "phone" to phone))
}

private fun register(name: String, phone: String) {
    Api().registration(name, phone)
        .responseObject(RegistrationResponse.Deserializer()) { _, response, result ->
            val registrationResponse = result.component1()
            if (registrationResponse?.success == 1) {
                showScreen()
            } else {
                showErrorDialog(registrationResponse?.errors?.phone?.firstOrNull())
            }
        }
}

问题是当发生错误时, phone 数据类中的变量(注册响应?错误?.phone)已填充 null ,但不是“不正确的电话号码”。