I have noticed that the recommendation from Elasticsearch team is changed
to use Java Rest Client instead of Transport one. The rationale behind it
looks convincing and it can also help Metron to be more decoupled from
Elasticsearch roadmap, so Metron users can upgrade Elasticsearch with
minimum dependency to Metron support.https://www.elastic.co/blog/state-of-the-official-elasticsearch-java-clients
P.S: Transport client will be deprecated in ES 7 and will be removed
completely on 8.