[kamikazeayoup]

Problem

The B3 multi-header propagator injects X-B3-Flags for debug requests but omits it from fields().

The propagator documentation instructs callers to clear these fields before reusing a carrier. Because the debug header is missing from the list, it survives cleanup and can cause a subsequent unsampled request to be treated as sampled.

Changes

Add B3Propagator.DEBUG_HEADER to FIELDS so callers can clear it before reusing a carrier.

Update fieldsList_multiInject to include the debug header and add inject_ReusedCarrier_DoesNotRetainDebugFlag to verify that a reused carrier does not retain the previous request’s debug flag.

Validation

• ./gradlew :extensions:trace-propagators:check passed locally.
• ./gradlew nativeTest --no-configuration-cache --no-parallel passed locally with Oracle GraalVM 25.0.4+7.1, the same version used by CI.

The GraalVM 25 compilation error reported in CI did not reproduce in this local run.

[opentelemetry-pr-dashboard]

Pull request dashboard status

Merged · refreshed 2026-10-22 13:42 UTC

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.65%. Comparing base (387f5c5) to head (1309335).

Additional details and impacted files

@@            Coverage Diff            @@
##               main    #8930   +/-   ##
=========================================
  Coverage     90.65%   90.65%           
  Complexity    10887    10887           
=========================================
  Files          1015     1015           
  Lines         29731    29732    +1     
  Branches       3876     3876           
=========================================
+ Hits          26953    26954    +1     
  Misses         1860     1860           
  Partials        918      918           

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[kamikazeayoup]

/dashboard route:reviewers

I investigated the failed GraalVM 25 check. Native compilation fails inside JUnit with “mismatch with existing registration.” As noted in the PR description, both the propagator checks and native tests passed locally with the same GraalVM version, and I couldn’t reproduce the CI failure.
Could a maintainer rerun the failed job?

[opentelemetry-pr-dashboard]

@kamikazeayoup, this pull request was routed to reviewers. The handoff remains active across pushes until newer actionable human feedback arrives. Top-level feedback through this request will not return; unresolved review threads remain open.

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