better handling of handshake failure exception

ebulk-data/embulk-wendelin-dataset-tool/lib/embulk/wendelin_client.rb

@@ -221,8 +221,12 @@ class WendelinClient
               http.request(req)
             end
     rescue Exception => e
+      puts
       @logger.error("HTTP ERROR: " + e.to_s, print=TRUE)
       @logger.error(e.backtrace)
+      if e.to_s.include? "handshake_failure" or e.to_s.include? "protocol_version"
+        @logger.error("This issue could be due to a cipher or certificates problem, please check your frontend instance or try with a http url", print=TRUE)
+      end
       return {"success"=>FALSE, "message"=>HTTP_MESSAGE_EXCEPTION}
     else
       if res.kind_of?(Net::HTTPSuccess) # res.code is 2XX