mongo-hadoop java connector Iterate through all collections

Question

I am trying to use this hadoop mongo connector,

https://github.com/mongodb/mongo-hadoop

I have seen many examples of connecting to a particular mongo collection using something like this,

mongodbConfig.set("mongo.input.uri", "mongodb://localhost:27017/dbname.collection");

But I have to retrieve records across different collections, so won't be able to specify one specific collection in the input uri. I have been searching for this but unable to find anything related. Any idea on how to go about this. Thanks in advance.