Change event.name attribute into top-level event name field

[trask]

Fixes #4260

Changes

Converts event name from an attribute (event.name) into a top-level field.

[reyang]

LGTM, I left a nonblocking comment.

[cijothomas]

💯 Looks good!
(coming from .NET, C++, Rust clients where EventName was a top-level field all the time.)

[XSAM]

I like this design ❤️

[lalitb]

+1 for this. Rust tokio tracing library already has "event name" as top-level field. Would be easy to model this into otel-rust with this change.

[CodeBlanch]

Looks like I'm late to the game, but here's some thoughts...

• In .NET ILogger API we have CategoryName always and optional EventId structure (which contains Name & Id). So what goes here? EventId.Name may not be present and if it is, presumably, it is only unique the context of a CategoryName. So should this be prefixed? EventName = $"{CategoryName}.{EventName}" or do we also need something like EventNamespace defined?

• Seems odd to introduce "Event" into the Log API given there is an "Event" API defined right below. Seems to invite confusion 😄 Why not just "Name" here?

[trask]

Seems odd to introduce "Event" into the Log API given there is an "Event" API defined right below

check out discussions at https://cloud-native.slack.com/archives/C062HUREGUV/p1733358994263159

since it's low level API it should support all logs features (including events), so it should take a name

and https://cloud-native.slack.com/archives/C062HUREGUV/p1733398117155609

The whole reason why the Go SIG was asking that the "Emit an Event" should be optional in the OTEP (see: open-telemetry/oteps#265 (comment)) is that after spending about a year designing the Logs API and SDK we felt that adding a separate method is a wrong decision.

[trask]

Why not just "Name" here?

it's going to map to new proto field event_name (open-telemetry/opentelemetry-proto#600)