Logstash 6.0.0 does not accept multiple types

[yanlow]

In Logstash 6.0.0 and beyond, types are depreciated.

As per: https://www.elastic.co/guide/en/elasticsearch/reference/current/_basic_concepts.html#_type

Running this plugin with Logstash 6.0.0 results in:

[2017-12-13T09:37:48,242][WARN ][logstash.outputs.elasticsearch] Could not index event to Elasticsearch. {:status=>400, :action=>["index", {:_id=>nil, :_index=>"logstash-2017.12.13", :_type=>"doc", :_routing=>nil}, #<LogStash::Event:0x4fb5b562>], :response=>{"index"=>{"_index"=>"logstash-2017.12.13", "_type"=>"doc", "_id"=>"Z6M8T2AB7kMplOyWulSi", "status"=>400, "error"=>{"type"=>"illegal_argument_exception", "reason"=>"Rejecting mapping update to [logstash-2017.12.13] as the final mapping would have more than 1 type: [elixir, doc]"}}}}

[yanlow]

#19 Removes all occurrences of types