handling
open fun handling(group: String, subscription: String, context: String, stream: EventStreamRecord, trace: Map<String, String>, topic: String?): Observation
subscription of context, run in the log or lease group, handling stream, retries included; trace holds the propagation fields the entry carries. topic is the topic the entry was read from (a consumption), null for the context's log. A subscription is one by its group and its name: each context has its own snapshot.