Kong grpc fails without proto file in grpcurl

Hello I have service/route in my local kong .

I have grpc server with reflection in python. It works fine on 50051 port where grpc server is on. but when ran from kong without proto file doesnt get valid response

With -proto option using kong 9080 it though works. But want to know wht am missing as to why its failing without proto option

:~# ./grpcurl -v -d ‘{“name”: “Kong 1.3!”}’ -plaintext localhost:50051 helloworld.Greeter/SayHello

Resolved method descriptor: rpc SayHello ( .helloworld.HelloRequest ) returns ( .helloworld.HelloReply );

Request metadata to send: (empty)

Response headers received: accept-encoding: identity,gzip content-type: application/grpc grpc-accept-encoding: identity,deflate,gzip

Response contents: { “message”: “Hello, Kong 1.3!!” }

Response trailers received: (empty) Sent 1 request and received 1 response

:~# ./grpcurl -v -d ‘{“name”: “Kong 1.3!”}’ -plaintext localhost:9080 helloworld.Greeter/SayHello

Error invoking method “helloworld.Greeter/SayHello”: failed to query for service descriptor “helloworld.Greeter”: server does not support the reflection API