When using Camel MongoDB component with "operation=findById" and [_id] field is happened to be a standard ObjectId(), it doesn't work anymore in v.2.18 (worked 2.17.3 and before).
Basically, to test you'd need to send org.bson.types.ObjectId in the message body but it never finds a document.
The problem lies in MongoDbProducer.createDoFindById().
Can be fixed by replacing line:
String id = exchange1.getIn().getMandatoryBody(String.class);
Object id = exchange1.getIn().getMandatoryBody();