Database
[{"_id":"some-id","_class":"org.some.class","number":1015,"timestamp":{"$date":"2020-09-05T12:08:02.809Z"},"cost":0.9200000166893005}]
Query
db.collection.aggregate([{$match:{"_id.country":{$exists:false}}},{$addFields:{"_id":{"productId":"$_id","country":"DE"}}},{$project:{"_id":1,"_class":1,"number":1,"timestamp":1,"cost":1}},{$out:"productDetailsV2"}])