[OpenTracing Shim] Support TraceFlags-only propagation without parent span

[ChenX1993]

Resolves #5339

Support propagating the TraceFlags without parent spans, e.g. the usecase of jaeger-debug-id.

[linux-foundation-easycla[bot]]

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• :white_check_mark: login: ChenX1993 / name: Chen Xu (e912fe97cb14546072f79533ed183a825c6979b5)

[codecov[bot]]

Codecov Report

Patch coverage: 35.71% and project coverage change: -0.11 :warning:

Comparison is base (0a2dd9e) 91.38% compared to head (e912fe9) 91.27%.

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #5380      +/-   ##
============================================
- Coverage     91.38%   91.27%   -0.11%     
- Complexity     4959     4964       +5     
============================================
  Files           549      550       +1     
  Lines         14563    14589      +26     
  Branches       1356     1358       +2     
============================================
+ Hits          13308    13316       +8     
- Misses          868      886      +18     
  Partials        387      387              

Impacted Files	Coverage Δ
...y/opentracingshim/PropagatedOpenTelemetrySpan.java	25.00% <25.00%> (ø)
.../io/opentelemetry/opentracingshim/Propagation.java	88.88% <100.00%> (+0.65%)	:arrow_up:
...opentelemetry/opentracingshim/SpanBuilderShim.java	94.82% <100.00%> (ø)

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[jkwatson]

@carlosalberto Can you take a look? This doesn't seem out-of-line to me, but I really don't know much about OT.

[jack-berg]

@carlosalberto bump. Does this impact stabilizing the shim in #5371?

[carlosalberto]

I'd say NO - the reason is that is not covered in the Compatibility spec right now (which is stable already). I will prepare a PR to the Spec to update this condition. My impression is that this shouldn't be impacting the expected behavior (as Jaeger already supported this, and it's a corner case for them).

cc @yurishkuro

[carlosalberto]

(In case I wasn't clear, while I prepare the Spec PR for this, I suggest we don't include this in the upcoming release)

[carlosalberto]

Ping @ChenX1993

[ChenX1993]

Sorry for the late reply. @yurishkuro Thanks for the remind @carlosalberto

[carlosalberto]

Ping @yurishkuro

[carlosalberto]

Ping @yurishkuro

[jack-berg]

Closing this PR as stale. Please re-open if interested in continuing the effort.