Stabilize `otel.event.name` attribute

[lmolkova]

Used by appenders and processors for mapping from bridges to OTel and nothing else (does not go over the wire).

Prototypes needed for stabilization:

• Log4j
• Logback
• Go (log processor) - https://pkg.go.dev/go.opentelemetry.io/otel/sdk/log#example-Processor-EventName

Behavior:

• bridge sets it as EventName top-level and does not set the attribute
• OR a log processor sets the top-level EventName

This allows to decouple new thing vs event.name which has different meaning (goes over the wire, has prior instrumentations and behavior).

We should also re-deprecate event.name.
EDIT (pellared): Done in #2914

[pellared]

and nothing else (does not go over the wire).

What about OTel Collector? Couldn't it also be responsible for changing otel.event.name attribute to EventName field?

What about exporting event records for non-OTLP exporters?

Reference:

• Revive event.name attribute #2597 (originally the issue proposed having the otel. prefix)

[pellared]

Updating the OTel Go example in the docs:

• sdk/log: update ExampleProcessor_eventName to use otel.event.name attribute opentelemetry-go#7568

Would be nice to have the semconv first.