Parent/child with logstash 2.0 or 2.1

I would like to migrate my elasticsearch cluster to 2.x but I am blocked with a problem on indexing child documents with Logstash.
In 1.6 I had something working but parent/child relation has changed since 2.0 and I don't know if it is possible in 2.x versions.
I tried to use a _parent field with the value of the parent id but it did'nt work.
Does someone has an example of logstash config working with Elasticsearch 2.x and with childs documents ?


This functionality was just barely added in

A version of the plugin with this update will be released soon.

Thanks for your answer, that's a good news.