当backend服务器不返回content-type,bfe会自动添加一个，这个怎么解决？

[lf2186]

最近上线业务，碰到一个问题，
当backend的response header为：
< HTTP/1.1 200 OK

• Server Apache-Coyote/1.1 is not blacklisted
  < Server: Apache-Coyote/1.1
  < Access-Control-Allow-Origin: *
  < Access-Control-Allow-Methods: POST, GET, OPTIONS, DELETE
  < Access-Control-Max-Age: 3600
  < Access-Control-Allow-Headers: x-requested-with
  < Transfer-Encoding: chunked
  < Date: Fri, 21 Jan 2022 08:34:20 GMT

经过bfe的调度，会变为：
< HTTP/1.1 200 OK
< Access-Control-Allow-Headers: x-requested-with
< Access-Control-Allow-Methods: POST, GET, OPTIONS, DELETE
< Access-Control-Allow-Origin: *
< Access-Control-Max-Age: 3600
< Date: Fri, 21 Jan 2022 08:31:15 GMT

• Server server is not blacklisted
  < Server: server
  < X-Write-By:server_global_2.0
  < Content-Type: text/plain; charset=utf-8
  < Transfer-Encoding: chunked

多了Content-Type: text/plain; charset=utf-8，会导致二进制数据流变为文本被浏览器解析，这个怎么让bfe不要添加？？

[daimg]

The behavior, appending "Content-Type" if not present, can not be disabled currently, but you may overwrite this header's value to expected one by mod_header .