Optional ReadonlyloadExact AttributeMap instance snapshots added for this invocation.
Optional ReadonlyloadExact ChannelMap pending-message snapshots added for this invocation.
Optional ReadonlylockAttributeMap instance locks added for this invocation.
Adds runtime-selected map instances to one RPC invocation.
Dex unions these selections with the fixed locks and loads from
@rpcordeclareRPCMethod. Locking and loading are independent, so read-modify-write handlers must select the same AttributeMap instance in both fields.