Conectando o Spark a várias coleções do Mongo

JavaSparkContext newcontext = new JavaSparkContext(session.sparkContext());
Map<String, String> readOverrides = new HashMap<String, String>();
readOverrides.put("collection", "details");
readOverrides.put("readPreference.name", "secondaryPreferred");
ReadConfig readConfig = ReadConfig.create(newcontext).withOptions(readOverrides);
MongoSpark.load(newcontext,readConfig);