Contribute upstream: span stacktrace

[SylvainJuge]

• suggest contribution in the SIG meeting/discussion: capture code.stacktrace and mutable spans open-telemetry/opentelemetry-java-instrumentation#10973
• if no, then nothing changes and we can close this issue for now.
• if yes, then next steps are likely:
  • create PR (in java-contrib repo) to contribute upstream, which might also require to also contribute our custom way to modify the spans stacktrace span processor open-telemetry/opentelemetry-java-contrib#1255
  • replace the current implementation with the upstream version once it has been released released in contrib 1.35.0 (release notes).

Additional challenges:

• we need to exclude the inferred spans, but inferred spans are specific to our distro for now (can we use a transient, not exported, span attribute on inferred spans to avoid this ?) --> Solved by adding an extra heuristic to filter which spans should have the attribute or not.

[SylvainJuge]

While the feature is now part of the 1.35.0 contrib release, it hasn't been published.

I've opened open-telemetry/opentelemetry-java-contrib#1297 to fix that, which hopefully will help us unblock this once the 1.36.0 release is available.

[SylvainJuge]

Currently blocked as the contrib 1.36.0 hasn't been released yet.