Logstash messages are not persistent

[CVTJNII]

With Logstash 2.2.2 I'm noticing message loss when the Logstash input listeners are restarted. Looking in the RabbitMQ management UI with the input listeners off I see none of the messages are marked as persistent. Looking in the code this is unexpected, the persistent bit should be true by default:

https://github.com/logstash-plugins/logstash-output-rabbitmq/blob/master/lib/logstash/outputs/rabbitmq.rb#L37
https://github.com/logstash-plugins/logstash-output-rabbitmq/blob/master/lib/logstash/outputs/rabbitmq.rb#L54

However, looking at the 'Message Durability' section of http://rubymarchhare.info/articles/durability.html I believe the persistent flag is being passed incorrectly. Per http://rubymarchhare.info/articles/durability.html the :persistent => @Persistent hash key should not be wrapped in :properties, but instead should be passed directly to @hare_info.exchange.publish.