In the API doc is stated:

By default, all read and write operations will be made on the primary, but it's possible to read from secondaries by changing the read preference:
mongoClient.setReadPreference(ReadPreference.secondaryPreferred());

However, this seems not to apply at least to the follwing methods because they are overriding the actual set ReadPreference by "ReadPreference.primary()":

• listDatabases()
• listDatabaseNames()
• getDatabase(dbName).listCollections()

This is very annoying because we want explicitly get this info from a secondary.