Http_poller fingerprint 不起作用

[375311384]

大家好：
             无法生成指纹字段，请帮助。配置文件如下：
   
input {
http_poller {
    urls => {
        test2 => {
            method => post
            url => "http://*.*.*.*:****/*/save"
	    	body => {
			params => {
				"id" => "#{id}"
			    "title" => "#{title}"
			    "mainBody" => "#{mainBody}"
				}
		}
            headers => {
			Accept => "application/json"
		}
         }
    }
    request_timeout => 60
    schedule => { cron => "* * * * * UTC"}
    codec => "json"
    metadata_target => "http_poller_metadata"
}
}


filter {
  fingerprint {
    concatenate_sources => "true"
	method => "MURMUR3"
	source =>  ["title","mainBody" ]
	concatenate_sources => true 
	target => "finger"
	#add_field => {"similar" => "%{finger}"}
  }
  
}

output {  
 elasticsearch {          
hosts  => "localhost:9200" 
index  => "*"
document_type => "*"
 }
  # stdout {
  #  codec => rubydebug
  # }
}