Kotlin中列表的Gson反序列化

这就是我的json

{
  "sub": "9",

  "auth_time": 1559381757,
  "idp": "idsrv",

  "role": [
    "Employer",
    "Employee",
    "Student"
  ],


  "iss": "",
  "aud": "",
  "exp": 1574933757,
  "nbf": 1559381757
}

这是我要将此Json转换为的对象。

data class Claims (
    @SerializedName("nameid") val nameId: String,
    @SerializedName("unique_id") val uniqueId: String,
    @SerializedName("sub") val sub: String,
    @SerializedName("unifiedNumber") val unifiedNumber: String,
    @SerializedName("role") var roleList: List<Role>
)

我为列表类型编写了一个自定义反序列化程序(在Java中工作)

class RoleDeserializer : JsonDeserializer<List<Role>> {

    private var roleId = 0
    @Throws(JsonParseException::class)
    override fun deserialize(json: JsonElement, typeOfT: Type, context: JsonDeserializationContext): MutableList<Role> {
        val resultList = ArrayList<Role>()
        if (json.isJsonArray) {
            for (e in json.asJsonArray) {
                resultList.add(Role(id = roleId++, name = e.asString))
            }
        } else if (json.isJsonObject) {
            resultList.add(Role(id = roleId++, name = json.asString))
        } else if (json.isJsonPrimitive) {
            if ((json as JsonPrimitive).isString)
                resultList.add(Role(id = roleId++, name = json.getAsString()))
        } else {
            throw RuntimeException("Unexpected JSON type: " + json.javaClass)
        }
        return resultList
    }
}

这就是我注册类型适配器的方式

val listType: Type = object : TypeToken<List<Role>>() {}.type
        val gson = GsonBuilder().registerTypeAdapter(listType, RoleDeserializer()).create()
        val claims = gson.fromJson(stringJson, Claims::class.java)

我仍然收到一个解析异常,声明

java.lang.IllegalStateException: Expected BEGIN_OBJECT but was STRING at line 1 column 161 path $.role[0]

我的RoleDeserializer永远不会被调用。注册类型适配器时我做错了什么吗?