How to use logstash-input-http-poller from zabbix api method?

i try use Http_poller input plugin loading Zabbix data, but cannot use ZABBIX api method loading data.

how to use zabbix jsonrpc api method in the logstash Http_poller input plugin ????
Are there any cases in this regard?

my logstash confiure, but logstash rufus-scheduler intercepted an error
input {
http_poller {
#interval => 15
codec => "json"
urls => {
zab => {
url => "http://ntmp.eoss.bba/zabbix/api_jsonrpc.php"
method => post
headers => {
"content-type" => "application/json"
}
body => {
jsonrpc => "2.0"
method => "apiinfo.version"
params => {
user => "v0002715"
password => "8ik,&UJMjk"
}
id => 1
}
#auth => null
}
}
request_timeout => 60
schedule => { cron => "* * * * * UTC"}
}
}

output {
stdout { codec => rubydebug }
}

error info
{ 2012 rufus-scheduler intercepted an error:
2012 job:
2012 Rufus::Scheduler::CronJob "* * * * * UTC" {}
2012 error:
2012 2012
2012 NoMethodError
2012 undefined method `encoding' for #Hash:0x2cbae460

I am not sure, but I think the code expects the body option to be a string, not a hash.

how to change code type in the input body option?