OpenTelemetry has introduced the Span type which is very similar to System.Diagnostics.Activity. In general .NET libraries expected to use System.Diagnostics APIs to publish the tracing data. We need to support the scenario of allowing the .NET libraries exporting the published data through OpenTelemetry. As the OpenTelemetry exporting APIs work with the Span class, we need to ensure all features supported by the Span class can be achieved by the Activity class too and fill any gap between the Span and Activity.
Although Activity has some more properties than Span (e.g. Parent property), Span also support some properties which not exist in Activity. This document is listing these missing properties and proposing the APIs we need to add to Activity. Most of the proposed additions here are almost identical to what OpenTel