timestamp dropped

[portermahoney]

This block of code in the gelf.rb file seems to modify timestamp and then remove it. Looks like a bug to me. I like to see the timestamp field not dropped.
Thanks!

https://github.com/logstash-plugins/logstash-input-gelf/blob/master/lib/logstash/inputs/gelf.rb#L112

if event["timestamp"].is_a?(Numeric)
event.timestamp = LogStash::Timestamp.at(event["timestamp"])
event.remove("timestamp")
end