Currently it's very difficult to find the API documentation for any types from mongod-driver-core. They are published (e.g. at http://mongodb.github.io/mongo-java-driver/4.1/apidocs/), but there is no direct link to that, so the only way to get to these types is via links from one of the top-level drivers (e.g. http://mongodb.github.io/mongo-java-driver/4.1/apidocs/mongodb-driver-sync/com/mongodb/client/MongoCollection.html#countDocuments(com.mongodb.client.ClientSession,org.bson.conversions.Bson,com.mongodb.client.model.CountOptions)). And some classes don't have any direct links to them, e.g. most of the exception types. So they are very difficult to find as a result.

A couple of options to consider:

1. Just add a link to the mongodb-driver-core API docs to http://mongodb.github.io/mongo-java-driver/4.1/apidocs/
2. Add the shared types to each of the top-level driver API docs. So there would be four copies of all the shared types published, but they would at least be easy to find from each of the top-level drivers.