This plugin is built with Buck.
Clone or link this plugin to the plugins directory of Gerrit's source tree, and issue the command:
buck build plugins/kafka-events
The output is created in
buck-out/gen/plugins/kafka-events/kafka-events.jar
This project can be imported into the Eclipse IDE:
./tools/eclipse/project.py
How to build the Gerrit Plugin API is described in the Gerrit documentation.