Querying subdocuments using whereIn by "_id" field does not work, yet it does by "id" key

[fidan-mkdir]

Description:

Querying using whereIn("subarray._id", [...]) does not work, when subarray has an array of items with '_id' field. If you had subarray of items with 'id' instead of '_id' and then queried for "subarray.id" it would work.
However querying using whereRaw(['subarray._id' => ['$in' => ['id_value'']]]) works as expected. I tried transforming the array of _id strings into an array of ObjectIds but it didn't help.

Steps to reproduce

1. Create a document with a subarray of items where each item will have an _id field
2. Try a query using whereIn("subarray._id", [...]) = will not return results
3. Now do the same but create a document with a subarray of items where each item will have an id field
4. Try a query using whereIn("subarray.id", [...]) = will return results

Expected behaviour

It should work as normal, as in step 4

Actual behaviour

It returned no results while there definitely were matches

[GromNaN]

Fixed by #3040