How to set timestamps in nested arrays - nestjs

Question

Versions
System: windows 10
NodeJS: v12.16.2
Typescript: v 4.1.3
Compiler / Transpiler: tsc
Typegoose(GIT): commithash
mongoose: 5.10.18
nestjs / nestjs-typegoose: 7.5.1 / 7.1.38
My question is how to set timestamps in nested arrays;
Example code here
I tried the code:
#ModelOptions({ schemaOptions: { timestamps: true } })
class childModel {
#prop()
param:String
}
class parentModel {
#prop({ type: childModel})
child:childModel[]
}
When I saved this model: parentModel.create( [{ param: 'xxx' }] ) , then the result is:
{
child:[
{
param:'xxx',
"createdAt": "2021-02-06T03:36:02.806Z",
"updatedAt": "2021-02-06T03:36:02.806Z"
}
]
}
but what I want is:
{
child:[
[
{
param:'xxx',
"createdAt": "2021-02-06T03:36:02.806Z",
"updatedAt": "2021-02-06T03:36:02.806Z"
}
]
]
}
then I tried the code:
#ModelOptions({ schemaOptions: { timestamps: true } })
class childModel {
#prop()
param:String
}
class parentModel {
#prop({type:[[childModel]]})
child:childModel[][]
}
saved like this parentModel.create( [ [ { param: 'xxx' } ] ] ) and result is:
{
child:[
[
{
param:'xxx'
}
]
]
}
No timestamps here,why?
I have seen some other similar problems, but I still don't understand ; maybe my English is too poor to understand, if you know, please tell me straightly.
Also Created an Issue on the typegoose Repo #485