使用MongoDB Stitch webhook服务函数，如何将返回的insertedId转换为字符串？

exports = function(payload, response) {
  const mongodb = context.services.get("mongodb-atlas");
  const collection = mongodb.db("your_database").collection("your_collection");

  const document = {
    name: "John Doe",
    age: 30
  };

  const result = collection.insertOne(document);
  const insertedId = result.insertedId.toString();

  response.setStatusCode(200);
  response.setHeader("Content-Type", "application/json");
  response.setBody(JSON.stringify({ insertedId }));
};