Need clarification on sending data as json

[kaisecheng]

Tell us about the issue

Description:
User has confusion about how to send data in json format as the document misses to point out the requirement of body and body_format.

body_format => "json" works only when body is an array or a hash

URL: https://www.elastic.co/guide/en/logstash/current/plugins-filters-http.html#plugins-filters-http-body https://www.elastic.co/guide/en/logstash/current/plugins-filters-http.html#plugins-filters-http-body_format

Anything else?