grok overwrite not working for empty strings

[Vad1mo]

So when I have this input

input="<14>2015-02-11T17:49:29Z logspout dev_ziservice_1[1]: ASDF"

  grok {      
    match => ["message", "<%{NUMBER}>%{TIMESTAMP_ISO8601:syslogTimestamp} %{SYSLOGHOST} %{DATA:container_name}(?:\[%{POSINT}\])?:%{SPACE}%{GREEDYDATA:message}"]
    overwrite => [ "message" ]
  }

message is = ASDF

if I have this input="<14>2015-02-11T17:49:29Z logspout dev_ziservice_1[1]: "
or this="<14>2015-02-11T17:49:29Z logspout dev_ziservice_1[1]:"

The message is not " " or "" like displayed in http://grokdebug.herokuapp.com/

[harshamadala]

Is there any workaround for this?

[jsvd]

moved this issue to logstash-plugins/logstash-filter-grok#77