Since MongoDatabase instances are immutable, it's quite confusing to have mutable Mongo/MongoClient properties that have no effect on MongoDatabase/MongoCollection instances. In particular,

MongoClient client = new MongoClient();   // w : 1
client.setWriteConcern(WriteConcern.REPLICA_ACKNOWLEDGED);
MongoDatabase database = client.getDatabase();  // w : 1
database.insertOne(new Document(...));   // still w : 1

This is different than the behavior of the now-deprecated Mongo#getDB method.

So we should document this, and at the same time deprecate the following methods on Mongo:

• setReadPreference
• setWriteConcern
• setOptions
• resetOptions
• addOption
• getOptions