spring boot 1.5.1 and elasticsearch 5.4

I have a spring boot 1.5.1 application and live Elasticsearch 5.4 which I can't downgrade to 2.4.5 or so Spring data supports only 2.x.x versions of Elasticsearch https://jira.spring.io/browse/DATAES-285 What is the best way to make spring boot work with remote elasticsearch together with out spring-data?