go mongo驱动程序更新无法将对象数组设置为空

package main

import (
    "context"
    "fmt"
    "log"
    "time"

    "go.mongodb.org/mongo-driver/bson"
    "go.mongodb.org/mongo-driver/mongo"
    "go.mongodb.org/mongo-driver/mongo/options"
)

type MyStruct struct {
    ID          string   `bson:"_id"`
    ObjectArray []string `bson:"objectArray"`
}

func main() {
    // 获取MongoDB连接
    client, err := mongo.NewClient(options.Client().ApplyURI("mongodb://localhost:27017"))
    if err != nil {
        log.Fatal(err)
    }
    ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
    defer cancel()
    err = client.Connect(ctx)
    if err != nil {
        log.Fatal(err)
    }
    defer client.Disconnect(ctx)

    // 选择集合
    collection := client.Database("mydb").Collection("mycollection")

    // 定义更新条件
    filter := bson.M{"_id": "12345"}

    // 定义更新内容
    update := bson.M{"$set": bson.M{"objectArray": bson.A{}}}

    // 执行更新操作
    result, err := collection.UpdateMany(context.Background(), filter, update)
    if err != nil {
        log.Fatal(err)
    }
    fmt.Printf("更新了 %v 条文档\n", result.ModifiedCount)
}