Span.data is missing

[marandaneto]

https://develop.sentry.dev/sdk/event-payloads/span/

We don't have a field to set arbitrary data associated with the Span, wondering if we decided to drop it or was an oversight.

Context: getsentry/sentry-cocoa#932 (comment)

[marandaneto]

Span#data should exist but Transaction#data not, ideally Transaction is not even an exposed API, see #1251

cc @Tyrrrz @brustolin

[marandaneto]

iOS has it https://github.com/getsentry/sentry-cocoa/blob/ee1dcf28e0e2b87c24ff6d8dae7813b719b3a8ad/Sources/Sentry/SentrySpan.m#L51-L56

[marandaneto]

fwiw, SDKs are setting the span.data as span.data since its part of the spec but if calling transaction.data, it goes to the transaction.extra field

[maciejwalkowiak]

This has been already implemented once, and the decision was to wait with it until we hide/drop ITransaction interface: #1235

[marandaneto]

@maciejwalkowiak yep I recall that but since dropping ITransaction would still have the same problem, I'd just do the same as the other SDKs, ITransaction.data sets to the transaction.extra, I'm currently implementing the performance API for Dart and I've done the same.