Timezone problem with date filter plugin

Elastic Stack Logstash
1

Hi.

With this configuration,

$ cat test.conf 
input {
    stdin {
        codec           => "json"
    }
}
filter { 
    date {
        locale => "en"
        match => ["stat_time", "YYYY-MM-dd'T'HH:mm:ss.SSSZ"]
        timezone => "Asia/Seoul"
   }
   mutate {
      add_field => { "index_ymd" => "%{+YYYYMMdd}" }
   }
}
output {
   stdout { codec => rubydebug }
}

When input this..

{"stat_time":"2016-05-01T0:00:00.000+0900"}

output will be....

{
    "stat_time" => "2016-05-01T00:00:00.000+0900",
    "@version" => "1",
    "@timestamp" => 2016-04-30T15:00:00.000Z,
    "host" => "dev-elastic101.ncl.nhnsystem.com",
    "index_ymd" => "20160430"
}

Input treated like no 'Z'(+0900) provided.

My expectation

{
    "stat_time" => "2016-05-01T00:00:00.000+0900",
    "@version" => "1",
    "@timestamp" => 2016-05-01T00:00:00.000Z,
    "host" => "dev-elastic101.ncl.nhnsystem.com",
    "index_ymd" => "20160501"
}

There no different action between with or without this

        timezone => "Asia/Seoul"

Is there something I miss?

Logstash-5.0.0-alpha1 using.

2

Sorry,

I was a little confused.
Nothing wrong with logstash.

My input should be like

{"stat_time":"2016-05-01T09:00:00.000+0900"}