[feature request] Looking for a way to avoid traceparent header rewriting.

[ingevarr]

Component

OpenTelemetry.Instrumentation.Http

Is your feature request related to a problem?

HttpHandlerDiagnosticListener propagates/rewrites context irrespective of sampling decision and presence of traceparent header.

In our company we have custom client library built around HttpClient for some internal purposes. We manually create Activity and manually add traceparent header before request execution, and then suppress instrumentation with SuppressInstrumentationScope.Begin() to force underlying HttpClient to not emit it's own events to avoid duplication.

There is a problem when someone uses that library with Opentelemetry.Instrumentation.Http enabled:
HttpClient creates Activity despite the instrumentation suppressed, but doesn't touch traceparent if it already present. Although this Activity will not be recorded, it falls into HttpHandlerDiagnosticListener which rewrites present and valid traceparent header. This leads to trace corruption.

Why such behaviour was chosen? Do I have any options to change it?

What is the expected behavior?

Check presence of traceparent header before rewriting it like runtime DiagnosticsHandler does.

Which alternative solutions or features have you considered?

Add some settings to choose which behaviour to use.

Additional context

Besides current issue, it's not obvious to me why HttpClient fallback to Activity creation even if the sampler's decision is to drop it. I am trying to supress it, but as a result Activity is still being created. Moreover, it is created with Recorded == true property, but it will not be recorded actually.