Base on: https://github.com/kitttyHappy/flume-ng-elasticsearch6-sink

This version of the Flume ElasticSearch sink works with ElasticSearch 7.4.2 but to do so, some libraries used by Flume had to be updated to the newest versions, For this reason, many tests do not work retuning a pretty "jar hell" exception.

As Flume is packaged right now (sink and flume libraries in the same class loader) seems difficult to find another solution. The best way, without modifying Flume, would be a new ElasticSearch sink based on http API and built on top of a reactive framework.