Decode values from OTEL_RESOURCE_ATTRIBUTES

[lgfa29]

While using the Go SDK I noticed an inconsistency in how OTEL_RESOURCE_ATTRIBUTES baggage values are encoded and decoded. This was due to a difference in the version of the W3C Baggage spec used for baggage propagation and the OTEL_RESOURCE_ATTRIBUTES decoding.

open-telemetry/opentelemetry-specification#2670 updates the W3C Baggage spec version used by the Resource spec to require percent-decoding values from OTEL_RESOURCE_ATTRIBUTES.

[lalitb]

This seems to be for Go SDK. Please open it here - https://github.com/open-telemetry/opentelemetry-go/issues

[lalitb]

My bad. This is relevant for C++ SDK too :)

[lgfa29]

Ah yes, this started with a Go SDK change, but evolved into a spec change that affects all SDKs. Sorry for not making this clear in the original issue 😅

[github-actions]

This issue was marked as stale due to lack of activity.

[marcalff]

Related: #2579