Elastic with mongodb recommended architecture

Hi Guys,

I would like to use mongodb with elastic but without mongo river.
I found different plugins such as mongoose and 10gen-labs mongo-connector but is there any solution in java?
I would not use Mongodb-River, rather I'd create some tricky architecture. (I think it can be done if elastic stores only the index values and ids which point into mongodb. Then if the user runs a query elastic will provide related ids (very quickly) then I can query over the proper collection with the given ids which is also very fast)

What is your opinion?

Thanks!