Should not the default elasticsearch-document_type for the current logstash ES Output Plugin be _doc instead of doc ?
The preferred type name for ES(6.x) and default type name for ES(7.x) are _doc.
https://www.elastic.co/guide/en/elasticsearch/reference/6.7/removal-of-types.html
This creates an unnecessary hassle if these two are not in sync.
[WARN ] 2019-05-02 06:04:22.758 [[main]>worker0] elasticsearch - Could not index event to Elasticsearch. {:status=>400, :action=>["index", {:_id=>"TEST-104693", :_index=>"testbook", :_type=>"doc", :routing=>nil}, #LogStash::Event:0x2a09cda5], :response=>{"index"=>{"_index"=>"test_v1", "_type"=>"doc", "_id"=>"TEST-104693", "status"=>400, "error"=>{"type"=>"illegal_argument_exception", "reason"=>"Rejecting mapping update to [test_v1] as the final mapping would have more than 1 type: [_doc, doc]"}}}}