Move event.domain from InstrumentScope to LogRecord

[jack-berg]

In the 11/9 Log SIG we discussed whether it was appropriate for event.domain to be defined as an attribute in InstrumentationScope, or is more appropriate an attribute on LogRecord.

We reasoned that LogRecord is more appropriate as follows:

• Because InstrumentationScope is a build-time concept, its not appropriate to InstrumentationScopes with the same name / version / schema, but different attributes.
• Therefore, it wouldn't be appropriate to have a single InstrumentationScope emit events in more than one event.domain.
• This means that emitting events in different domains requires you to emit those events in different InstrumentationScopes.
• We did not intend event.domain to impact decisions about how broad or narrow a particular InstrumentationScope is. Perhaps the InstrumentationScope represents an entire application. It should be perfectly valid to emit events in different domains.

Conclusion: Move event.domain to an attribute on LogRecord.