Fix to contain te header in gRPC request

[minwoox]

Motivation:
According to the spec,
gRPC Request-Headers has to contain te header in order to detect incompatible proxies.

Modification:

• Add te header to gRPC request headers

Result:

• Fix Armeria failed to call python gRPC server #1963

[minwoox]

I didn't add a test case for this because the upstream server does not include te header while converting request headers to MetaData here.

[anuraaga]

Thanks!

[minwoox]

I also found out that the upstream metadata doesn't include the pseudo headers.
But we do have all pseudo headers and te. Do we need to follow the upstream's conversion strategy? @anuraaga

[ikhoon]

Thanks!

[anuraaga]

There's some context in grpc/grpc-java#5788

There isn't a clear definition of what headers should be in Metadata but you're right it's recommended to hide pseudoheaders and hop-by-hop ones. Since it's not defined and seems like an implementation detail, I just went with reduced complexity 😅

[codecov]

Codecov Report

Merging #1965 into master will decrease coverage by 0.04%.
The diff coverage is 100%.

@@             Coverage Diff              @@
##             master    #1965      +/-   ##
============================================
- Coverage     73.38%   73.34%   -0.05%     
+ Complexity     9103     9100       -3     
============================================
  Files           805      805              
  Lines         35474    35474              
  Branches       4355     4355              
============================================
- Hits          26032    26017      -15     
- Misses         7181     7209      +28     
+ Partials       2261     2248      -13

Impacted Files	Coverage Δ	Complexity Δ
.../armeria/common/grpc/protocol/UnaryGrpcClient.java	70% <ø> (ø)	5 <0> (ø)	⬇️
...m/linecorp/armeria/client/grpc/ArmeriaChannel.java	97.5% <100%> (ø)	8 <0> (ø)	⬇️
...rp/armeria/server/tomcat/ManagedTomcatService.java	50.84% <0%> (-22.04%)	6% <0%> (-1%)
...armeria/server/tomcat/Tomcat90ProtocolHandler.java	48.14% <0%> (-14.82%)	11% <0%> (-4%)
...om/linecorp/armeria/server/jetty/JettyService.java	63.05% <0%> (-2.96%)	23% <0%> (-1%)
.../linecorp/armeria/server/tomcat/TomcatService.java	63.29% <0%> (-2.66%)	22% <0%> (-1%)
.../com/linecorp/armeria/server/docs/ServiceInfo.java	70.73% <0%> (-2.44%)	16% <0%> (-1%)
...a/common/grpc/protocol/ArmeriaMessageDeframer.java	71.77% <0%> (+0.95%)	48% <0%> (+1%)	⬆️
.../main/java/com/linecorp/armeria/server/Server.java	82.43% <0%> (+1.35%)	17% <0%> (ø)	⬇️
...inecorp/armeria/server/grpc/ArmeriaServerCall.java	88.18% <0%> (+1.57%)	82% <0%> (+1%)	⬆️
... and 3 more

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[trustin]

Thanks, @minwoox !

[minwoox]

There's some context in grpc/grpc-java#5788

Ah, thanks! Yeah, it's not defined and I think it's fine as it is. :-)

[minwoox]

Thanks for reviewing!