Support W3C Baggage header

[jbogard]

Summary of the changes (Less than 80 chars)

• Adds support of W3C Baggage standard

Addresses #28319

[JamesNK]

All other headers are pascal case. This won't matter when getting the value from the headers collection - it is case-insensitive.

Suggested change

	public static readonly string Baggage = "baggage";
	public static readonly string Baggage = "Baggage";

[jbogard]

Yeah, I was curious about that. I kept it consistent with traceparent and tracestate, the other two headers related to this standard (W3C Trace Context) that are lowercase in this class.

[JamesNK]

Ok. Perhaps better as is then.

[Tratcher]

Since HTTP/2 all header names are officially lower case so it might make sense to start doing that with new entries. You're right though that the collections are all ignore-case so it shouldn't make a difference.

[Tratcher]

Since HTTP/2 all header names are officially lower case so it might make sense to start doing that with new entries. You're right though that the collections are all ignore-case so it shouldn't make a difference.

[Tratcher]

@shirhatti weren't we already planning on doing something like this?

[Tratcher]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 2 pipeline(s).

[shirhatti]

@shirhatti weren't we already planning on doing something like this?

Yes. We're planning to add support for the OpenTelemetry propagators API- https://github.com/open-telemetry/opentelemetry-specification/blob/master/specification/context/api-propagators.md

We'd still want to W3C trace context and W3C baggage propagation on by default with new API to configure/disable propagation. This change would be needed even if we add propagators support.

[Tratcher]

Thanks

[ghost]

Hi @Tratcher. It looks like you just commented on a closed PR. The team will most probably miss it. If you'd like to bring something important up to their attention, consider filing a new issue and add enough details to build context.