[Api] support for adding default tags to tracer

[alimahboubi]

Fixes #6016
Design discussion issue #6016

Changes

This pull request adds a new overload to the TracerProvider.GetTracer method to support the inclusion of tags, similar to the new ActivitySource constructor overload in .NET 9. This allows users to associate initial tags with a Tracer (and therefore the underlying ActivitySource), which can be used to differentiate application instances with different configurations. These tags are applied to all activities created by the ActivitySource.

The new overload is:

public Tracer GetTracer(string name, string? version = null, IEnumerable<KeyValuePair<string, object?>>? tags = null)

[Kielek]

@alimahboubi, it is good practice to execute build locally. In this case it should be done in Release mode. For now, I am not able to compile the code.

Could you please fix it?

[alimahboubi]

@Kielek Thanks for pointing that out! I've fixed the compilation error. I've also run a local build in Release mode to confirm

[alimahboubi]

@Kielek Thanks for the detailed feedback! I've incorporated both of your suggestions:

• The new GetTracer overload is now in the Unshipped file.

• I've updated the GetTracer signature to include the optional version and tags parameters, and adjusted the existing overload accordingly (removing the default parameter).

• I've updated the public contract part.

I've updated the commit with these changes. Please take another look!

[Kielek]

Your assertions are to weak. The goal is to have one instance per tags set. Now, you have multiple instances for the same set of tags.

If you include all changes, tests will be failing. You need to fix the TracerKey.

[Kielek]

Worth to add entry in CHANGELOG under OpenTelemetry.Api