时间戳不正确的输出logstash

Question

我的logstash conf.file是这样的：

input {
   udp {
      port => 12345
      codec => "json"
      type => "logback"
      }
}
filter {
   grok {
     match => {
      "message" => ".*(?<timestamp>\d{14}\.\d{4}[+-]\d{4})\d\d$"
              }
        }
   date {
     match => ["timestamp", "YYYY-MM-dd HH-mm"]
     remove_field => ["timestamp"]
        }
}
output {
 file {
  codec => line {format => "[%{@timestamp}] %{appname} [%{level}] [%{host}] --> %{[message]}"}
  path => "app.log"
  flush_interval => 10
 }
}

因此，代替我的过滤器，时间戳输出具有以下格式：

[2018-08-23T07:25:36.485Z]

我也得到了 [“ _ grokparsefailure”] ，但不知道为什么