Align GrpcSender contract with HttpSender

[jack-berg]

I was reviewing #6645 I was cringing at inconsistencies between GrpcSender and HttpSender.

• GrpcSender has void send(T request, Runnable onSuccess, BiConsumer<GrpcResponse, Throwable> onError)
• HttpSender has void send(Marshaler marshaler, int contentLength, Consumer<Response> onResponse, Consumer<Throwable> onError);

HttpSender got it right by cleanly separating out the difference between an export request that received a response, and one that ended exceptionally. Its up to the caller HttpExporter to evaluate the response and decide whether it was a success or error response. For GrpcSender, these are muddied together in a BiConsumer<GrpcResponse, Throwable>.

For #6645, when export attempts fail, we want to include exception in the CompletableResultCode which allow the caller to interpret what happened. Cleanly delineating between when a export failed but received a response, and failed exceptionally makes for a much cleaner API and user experience.

[codecov]

Codecov Report

Attention: Patch coverage is 81.25000% with 12 lines in your changes missing coverage. Please review.

Project coverage is 90.00%. Comparing base (71124d2) to head (95d8fbb).
Report is 18 commits behind head on main.

Files with missing lines	Patch %	Lines
...pc/managedchannel/internal/UpstreamGrpcSender.java	42.85%	4 Missing and 4 partials ⚠️
...telemetry/exporter/internal/http/HttpExporter.java	86.36%	2 Missing and 1 partial ⚠️
...telemetry/exporter/internal/grpc/GrpcExporter.java	96.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #6658      +/-   ##
============================================
- Coverage     90.10%   90.00%   -0.10%     
- Complexity     6287     6358      +71     
============================================
  Files           698      703       +5     
  Lines         18978    19145     +167     
  Branches       1861     1889      +28     
============================================
+ Hits          17100    17232     +132     
- Misses         1305     1334      +29     
- Partials        573      579       +6     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[breedx-splk]

Yeah, this is a good catch.

[breedx-splk]

Looks good, I like the alignment. I had a few small suggestions, but nothing to block this. Thanks!