user defined ObjectId with keystone.createItems gets overwritten with new _id

[Joel-Mckay]

Expected behavior
_id can be user defined for data/index restore operations

Actual/Current behavior
ignores old _id and generates new _id every time
(I am new to the api, so there may be a reason for this I haven't read about yet)

Steps to reproduce the actual/current behavior

 var keystone = require('keystone');
 var Types = keystone.Field.Types;
 const errors = require("errors");
 // ...
 //json object based on default User Model entry
 var backupAcc = JSON.parse('{"_id":"5d3f62bca9108026a732c9fa","logins":0,"password":"newTest","email":"mail@example.com","__v":0,"isAdmin":false,"name":{"last":"Sad","first":"Panda"}}');
 //
 // backupAcc['_id']='ObjectId("'+ backupAcc['_id']+'")';
 backupAcc['_id']= keystone.mongoose.Types.ObjectId( backupAcc['_id']);
 //
 var payload ={};
	 payload['User'] = Array();
	 payload['User'][0] = backupAcc;
 //
 keystone.createItems(payload, { verbose: true}, function (err, stats) { 
	 //wrong '_id' generated upon insert, delete, and insert again

Environment
Keystone 4
Node.js v12.6.0