in glean/src/core/metrics/events_database/recorded_event.ts [42:55]
private static withTransformedExtras(
e: Event,
transformFn: (extras: ExtraMap) => ExtraMap
): Event {
const extras = e.extra || {};
const transformedExtras = transformFn(extras);
return {
category: e.category,
name: e.name,
timestamp: e.timestamp,
extra: (transformedExtras && Object.keys(transformedExtras).length > 0)
? transformedExtras : undefined
};
}