Start mongod like:

mongod --replSet test

and try to send a command:

        MongoClient mongo = new MongoClient(new MongoClientURI("mongodb://localhost:27001"));
        CommandResult result = mongo.getDB("admin").command("ping");

It fails with this exception:

Exception in thread "main" com.mongodb.MongoServerSelectionException: Unable to connect to any servers

The root cause is that ClusterDescription.getAny() only returns server descriptions where isPrimary || isSecondary is true.