I am using ELK GA 6.0.0. I have messages in my Kafka topic serialized using Avro, and I would like to push them into my ES using Logstash. From this link; https://www.elastic.co/guide/en/logstash/6.0/plugins-codecs-avro.html I got to know that it is not a default plugin. I have no internet access in my ELK machine. So how can I manually install this, offline?