OpenTelemetry Support

[danilobreda]

Implementing this integration will allow us to gain valuable insights into Tracing and Metrics of messages as they flow through your system.

Masstransit details: https://masstransit.io/documentation/configuration/observability#tracing

[zlepper]

Just a note, there is already an OTEL package for Rebus: https://github.com/rebus-org/Rebus.OpenTelemetry :)

Though I would be all for moving it in core now that Otel is becoming more and more standardized :)