Embedded document _id of type ObjectId are introspected without native type @db.ObjectId

[janpio]

Prisma 1 MongoDB supported embedded documents. A document could for example look like this:

{
  "_id": {
    "$oid": "61ef1a40be07770008a7b87b"
  },
  "title": "title",
  "ids": [
    {
      "name": "name",
      "value": "value",
      "_id": {
        "$oid": "61ef1a8dbe07770008a7b87d"
      }
    }
  ]
}

create via this Prisma 1 schema:

type Foo {
  id: ID! @id
  title: String!
  ids: [IdSet!]!
}

This is currently introspected into this Prisma schema:

model Foo {
  id     String    @id @default(dbgenerated()) @map("_id") @db.ObjectId
  ids    FooIds[]
  title  String
}

type FooIds {
  id    String @map("_id")
  name  String
  value String
}

Note how FooIds.id is only of scalar type String although the data clearly shows it being $oid, which we could probably render as @db.ObjectId.

(We are not sure where the value comes from yet, so if this deserves the @default(dbgenerated()) as well, but suspect Prisma 1 did generate that manually and then inserted the value - as _id usually does not really exist for embedded types afaik.)