Logstash array length check

Elastic Stack Logstash
12

I can't reproduce:

$ cat input.json 
{ "timestamp":"2017-04-18 17:04:30", "message":"My logger is now ready", "messageLevel":"FATAL", "component":6, "transactionId":0, "test":"message", "test1":"message", "test2":"message", "test3":"message", "test4":"message", "test5":"message", "test6":"message", "test7":"message", "test8":"message", "test9":"message", "test10":"message", "test11":"message", "test12":"message", "test13":"message", "test14":"message", "test15":"message", "test16":"message", "test17":"message", "test18":"message", "test19":"message", "test20":"message", "test21":"message", "test22":"message", "test23":"message", "test24":"message", "test25":"message", "test26":"message" }
$ cat test.config 
input { stdin { codec => json_lines } }
output { stdout { codec => rubydebug } }
filter {
  ruby {
    code => "
      event['count'] = event.to_hash.length
    "
  }
}
$ /opt/logstash/bin/logstash -f test.config < input.json
Settings: Default pipeline workers: 8
Pipeline main started
{
        "timestamp" => "2017-04-18 17:04:30",
          "message" => "My logger is now ready",
     "messageLevel" => "FATAL",
        "component" => 6,
    "transactionId" => 0,
             "test" => "message",
            "test1" => "message",
            "test2" => "message",
            "test3" => "message",
            "test4" => "message",
            "test5" => "message",
            "test6" => "message",
            "test7" => "message",
            "test8" => "message",
            "test9" => "message",
           "test10" => "message",
           "test11" => "message",
           "test12" => "message",
           "test13" => "message",
           "test14" => "message",
           "test15" => "message",
           "test16" => "message",
           "test17" => "message",
           "test18" => "message",
           "test19" => "message",
           "test20" => "message",
           "test21" => "message",
           "test22" => "message",
           "test23" => "message",
           "test24" => "message",
           "test25" => "message",
           "test26" => "message",
         "@version" => "1",
       "@timestamp" => "2017-04-18T13:19:47.223Z",
             "host" => "lnxolofon",
            "count" => 35
}
Pipeline main has been shutdown
stopping pipeline {:id=>"main"}