WIP can be seen [here](https://github.com/seznam/beam/pull/41) (there are still few parts missing) and we have to rethink logic when it comes to early triggering (i reckon we can not support it at all)
cc @b923 [ Full content available at: https://github.com/apache/beam/pull/6306 ] This message was relayed via gitbox.apache.org for devnull@infra.apache.org
