Optionalprovider: IMetadataProviderOptionalcontextUser: UserInfothe row's fields, or null when there is no key to read by, the read is refused, or
the record no longer exists. Callers should treat null as "not mine / nothing to do"
rather than as a failure — a refused read is the expected outcome for a session that
may not see the record.
The row behind an entity event, however it has to be obtained.
Three sources, in order:
event.baseEntityis the live instance; its fields are already in hand.recordData— the entity is on the broadcast allowlist; parse it.recordData— re-read the one record by primary key throughprovider, ascontextUser. This is the access-controlled path, and it is the only one that can supply fields the primary key does not carry (a detail'sConversationID, say).