addEvent method
Adds an event to the Span. Ignored if isEnded Note that the OpenTelemetry project documents certain "standard event names and keys" which have prescribed semantic meanings. See https://github.com/open-telemetry/semantic-conventions/blob/main/docs/README.md
Implementation
void addEvent(SpanEvent spanEvent) {
if (_modifiable && !_hasEmptyName(spanEvent.name)) {
_spanEvents ??= [];
_spanEvents!.add(spanEvent);
}
}