Elasticsearch Java plugin and logstash - need help



I need some help with an elasticsearch Java plugin and logstash:
According to https://www.elastic.co/guide/en/elasticsearch/reference/master/modules-scripting.html#native-java-scripts I created a plugin for elastic using AbstractExecutableScript.

What I want is to manipulate some data within this script.
When I now send some data via logstash to my cluster, this plugin is never called.

Does anyone have a hint for me?
What could be wrong?
Or even better, does anyone has a working example?

Thanks and regards

(system) #2