Allow empty arrays as values in grammar

[piavlo]

Allow following config not to fail with parse error

filter {
  grok {
    tags                => [ "apache-accesslog" ]
    patterns_dir        => [ "/opt/logstash/patterns" ]
    match               => [ "clientip", "%{IP}" ]
    break_on_match      => true
    named_captures_only => true
    tag_on_failure      => [ ]
  }
}

[piavlo]

@jordansissel - nagging since #405 was merged and this one is kind of related - as example in case we do not want to add any tags on parse failure.
And in general there is probably nothing wrong if grammar accepts empty arrays/hashes as possible values?

[piavlo]

@jordansissel - nagging since #405 was merged and this one is kind of related - as example in case we do not want to add any tags on parse failure.
And in general there is probably nothing wrong if grammar accepts empty arrays/hashes as possible values?