New "asset" object on Activities V2 events

Broker API

Activity V2 events now include an optional asset object identifying the instrument the activity relates to.

• id and symbol are present when the activity maps to a known asset.
• For options activities, the object describes the option contract, not the underlying.
• isin and cusip are included where licensing permits.
• Existing trade detail fields are unchanged and remain available.

Affected Endpoints

• GET /v2beta1/events/activities
• GET /v2beta1/accounts/{account_id}/events/activities/{event_id}