Splitting on one element only, in array field causes additional suffix

[zdharmawan]

Hi all,

I have this as my logstash.conf

input {
  stdin {
  }
}
filter {
    split {
      field => "Series"
    }
  }
}
output {
  stdout {
    codec => rubydebug
  }
}

Normally, the content of the "Series" has more than one element, but for some reason sometime it outputs only one element. The Input is like this

{"Series":[{"DataType":"AirQuality.1","Timestamp":"2016-03-07T03:36:03.119000Z","DataKeyValuePairs":{"aqi":"0","om":"a","pwr":"0","cl":"0","aqil":"0","fs1":"112","fs2":"960","fs3":"2880","fs4":"2880","dtrs":"0","aqit":"29","clef1":"n","repf2":"n","repf3":"n","repf4":"n","fspd":"1","tfav":"130","psens":"1"}}]}

For some reason on the output side is adding a sequence as suffix, like this

      "@version" => "1",
    "@timestamp" => "2016-03-08T14:20:30.475Z",
        "Series" => [
       [0] {
                    "DataType" => "AirQuality.1",
                   "Timestamp" => "2016-03-07T03:36:03.119000Z",
           "DataKeyValuePairs" => {
                 "aqi" => "0",
                  "om" => "a",
                 "pwr" => "0",
                  "cl" => "0",
                "aqil" => "0",
                 "fs1" => "112",
                 "fs2" => "960",
                 "fs3" => "2880",
                 "fs4" => "2880",
                "dtrs" => "0",
                "aqit" => "29",
               "clef1" => "n",
               "repf2" => "n",
               "repf3" => "n",
               "repf4" => "n",
                "fspd" => "1",
                "tfav" => "130",
               "psens" => "1"
           }
       }
   ]

Is this a known bug?