如何使用Mongoose填充数组的数组？

const mongoose = require('mongoose');

const childSchema = new mongoose.Schema({
  name: String,
});

const parentSchema = new mongoose.Schema({
  children: [[childSchema]],
});

const Parent = mongoose.model('Parent', parentSchema);

const parent = new Parent({
  children: [
    [{ name: 'Child 1' }, { name: 'Child 2' }],
    [{ name: 'Child 3' }, { name: 'Child 4' }],
  ],
});

parent.save((err, savedParent) => {
  if (err) {
    console.error(err);
  } else {
    console.log(savedParent);
  }
});