Merge net7 branch to main: Updates DiagnosticSource to 7.0.0 + net7 instrumentation improvements

[alanwest]

Work included is primarily from the following PRs

• [.NET7.0] AspNetCore ActivitySource Migration #3391
• [.NET7.0] Http client activity source migration #3415
• Use DiagnosticSource 7.0 and drop netcoreapp3.1 target #3351

[codecov]

Codecov Report

Merging #3539 (a243a4e) into main (2b6a3b0) will decrease coverage by 0.08%.
The diff coverage is 87.87%.

@@            Coverage Diff             @@
##             main    #3539      +/-   ##
==========================================
- Coverage   86.80%   86.71%   -0.09%     
==========================================
  Files         275      275              
  Lines        9949     9959      +10     
==========================================
  Hits         8636     8636              
- Misses       1313     1323      +10     

Impacted Files	Coverage Δ
...tp/Implementation/HttpHandlerDiagnosticListener.cs	72.63% <73.33%> (-0.87%)	⬇️
...tation.AspNetCore/Implementation/HttpInListener.cs	89.87% <100.00%> (+0.12%)	⬆️
...tion.AspNetCore/TracerProviderBuilderExtensions.cs	100.00% <100.00%> (ø)
....Instrumentation.Http/HttpClientInstrumentation.cs	100.00% <100.00%> (ø)
...umentation.Http/TracerProviderBuilderExtensions.cs	75.00% <100.00%> (+3.57%)	⬆️
...mentation/ExportClient/ExporterClientValidation.cs	30.00% <0.00%> (-70.00%)	⬇️
...c/OpenTelemetry/Internal/TagAndValueTransformer.cs	80.00% <0.00%> (-20.00%)	⬇️
...emetry.Api/Internal/OpenTelemetryApiEventSource.cs	76.47% <0.00%> (-5.89%)	⬇️
...rc/OpenTelemetry.Exporter.Zipkin/ZipkinExporter.cs	86.17% <0.00%> (-2.26%)	⬇️
...Exporter.Jaeger/ApacheThrift/Protocol/TProtocol.cs	91.30% <0.00%> (-0.86%)	⬇️
... and 8 more

[alanwest]

Fixed a few small things. I think this is good to merge. We definitely need a changelog - maybe there's some dependency on #3448, but assuming we're dropping netcoreapp3 as a target, we should probably update the changelog for all relevant packages. I'll stage up a follow up PR so we can continue the discussion.

[reyang]

These CI can be removed from the branch policy:

[xiang17]

Fixed a few small things. I think this is good to merge. We definitely need a changelog - maybe there's some dependency on #3448, but assuming we're dropping netcoreapp3 as a target, we should probably update the changelog for all relevant packages. I'll stage up a follow up PR so we can continue the discussion.

Will we have a version where we support both .NET Core 3.1 and .NET 7? There might be overlapping time where both are officially supported.

.NET Core 3.1 ends support in December 13, 2022.

Edit: .NET 7 is scheduled to release in November 2022. Only one month later. Maybe OTel will just release after .NET Core 3.1 ends support.

[alanwest]

Will we have a version where we support both .NET Core 3.1 and .NET 7? There might be overlapping time where both are officially supported.

@xiang17 Technically OpenTelemetry .NET would likely continue to work with netcoreapp3.1 even though we've upgraded to DiagnosticSource v7. A netcoreapp3.1 application could still add us as a dependency because we currently still target netstandard2.0. Though, users will receive a build warning. However, one option on the table in #3448 is to drop our netstandard targets.

That said, we haven't settled on a final strategy or timeline yet for how we'll coordinate our next stable release with the release of .NET 7.

[xiang17]

Sounds cool!

I was trying to validate what you said but got a build error after adding netcoreapp3.1 in one of the test projects, only to find the PR was only merged 10 days ago. So, no action for now. :D