grpc only: error-client-content-type-unsupported on "Content-Type:text/plain; charset=utf-8"

[jldec]

The grpc protocol handler is rejecting requests with Content-Type:text/plain; charset=utf-8

$ curl -H "Content-Type:text/plain; charset=utf-8" -d "should work" http://192.168.99.100:32300/requests/t1 -v

*   Trying 192.168.99.100...
* TCP_NODELAY set
* Connected to 192.168.99.100 (192.168.99.100) port 32300 (#0)
> POST /requests/t1 HTTP/1.1
> Host: 192.168.99.100:32300
> User-Agent: curl/7.54.0
> Accept: */*
> Content-Type:text/plain; charset=utf-8
> Content-Length: 11
> 
* upload completely sent off: 11 out of 11 bytes
< HTTP/1.1 500 Internal Server Error
< Date: Mon, 19 Feb 2018 18:59:29 GMT
< Content-Length: 0
< Content-Type: text/plain; charset=utf-8

[sidecar]: 2018/02/19 18:59:28 Sidecar for function 't1' (t1->replies) using grpc dispatcher starting
[sidecar]: 2018/02/19 18:59:28 Rebalanced: &{Type:rebalance start Claimed:map[] Released:map[] Current:map[]}
[sidecar]: 2018/02/19 18:59:28 Rebalanced: &{Type:rebalance OK Claimed:map[t1:[0]] Released:map[] Current:map[t1:[0]]}
[main]: Node started in 76ms
[main]: gRPC loaded in 94ms
[main]: HTTP loaded in 98ms
[main]: gRPC running on localhost:10382
[main]: HTTP running on http://localhost:8080
[main]: Function invoker started in 276ms
[sidecar]: 2018/02/19 18:59:29 <<< Message{, map[error:[error-client-content-type-unsupported] correlationId:[e2e941b9-68fa-4dd8-860e-ae399a55b974]]}

The same message sent with the http protocol is handled ok.

$ curl -H "Content-Type:text/plain; charset=utf-8" -d "should work" http://192.168.99.100:32300/requests/t1 -v
*   Trying 192.168.99.100...
* TCP_NODELAY set
* Connected to 192.168.99.100 (192.168.99.100) port 32300 (#0)
> POST /requests/t1 HTTP/1.1
> Host: 192.168.99.100:32300
> User-Agent: curl/7.54.0
> Accept: */*
> Content-Type:text/plain; charset=utf-8
> Content-Length: 11
> 
* upload completely sent off: 11 out of 11 bytes
< HTTP/1.1 200 OK
< Content-Type: text/plain; charset=utf-8
< Date: Mon, 19 Feb 2018 19:06:15 GMT
< Content-Length: 22
< 

[sidecar]: 2018/02/19 19:06:15 Sidecar for function 't1' (t1->replies) using http dispatcher starting
[sidecar]: 2018/02/19 19:06:15 Waiting for function to accept connection on localhost:8080
[sidecar]: 2018/02/19 19:06:15 Waiting for function to accept connection on localhost:8080
[sidecar]: 2018/02/19 19:06:15 Rebalanced: &{Type:rebalance start Claimed:map[] Released:map[] Current:map[]}
[sidecar]: 2018/02/19 19:06:15 Rebalanced: &{Type:rebalance OK Claimed:map[t1:[0]] Released:map[] Current:map[t1:[0]]}
[sidecar]: 2018/02/19 19:06:15 Waiting for function to accept connection on localhost:8080
[sidecar]: 2018/02/19 19:06:15 Wrapper received Message{should work, map[Content-Type:[text/plain; charset=utf-8] Accept:[*/*] correlationId:[0f4f98eb-55f1-47ca-92e3-5dd457e8fe90]]}
[sidecar]: 2018/02/19 19:06:15 Wrapper about to forward Message{should workshould work, map[Date:[Mon, 19 Feb 2018 19:06:15 GMT] Connection:[keep-alive] X-Powered-By:[Express] Content-Type:[text/plain; charset=utf-8] Content-Length:[22] Etag:[W/"16-weTPpPtGiPf2MRJe2B4n0af2bac"] correlationId:[0f4f98eb-55f1-47ca-92e3-5dd457e8fe90]]}
[sidecar]: 2018/02/19 19:06:15 <<< Message{should workshould work, map[Date:[Mon, 19 Feb 2018 19:06:15 GMT] Connection:[keep-alive] X-Powered-By:[Express] Content-Type:[text/plain; charset=utf-8] Content-Length:[22] Etag:[W/"16-weTPpPtGiPf2MRJe2B4n0af2bac"] correlationId:[0f4f98eb-55f1-47ca-92e3-5dd457e8fe90]]}