I am using BsonValue.Null for querying in filter
I am creating my filter like this:
Builders<T>.Filter.Eq("TransactionKey", BsonNull.Value) | Builders<T>.Filter.Eq("TransactionKey", string.Empty)

In Version 2.2 this query is rendered as
{ "$or" : [

{ "TransactionKey" : null }

,

{ "TransactionKey" : "" }

] }

but in Version 2.4.3 this query is rendered as
{ "$or" : [

{ "TransactionKey" : "BsonNull" }

,

{ "TransactionKey" : "" }

] }

So is the value of BsonValue.Null is changed from null to "BsonNull" purposely or is it a defect?