# index
https://www.elastic.co/guide/en/elasticsearch/reference/7.4/index.html1
# restful api
https://www.elastic.co/guide/en/elasticsearch/reference/7.4/rest-apis.html
# java api
https://www.elastic.co/guide/en/elasticsearch/client/java-api/7.4/index.html
# java-rest
https://www.elastic.co/guide/en/elasticsearch/client/java-rest/7.4/index.html
# java-rest-high
https://www.elastic.co/guide/en/elasticsearch/client/java-rest/7.4/java-rest-high.html
