failedAt

When the entry acted on was parked (epoch milliseconds, the entry's failedAt), as the caller saw it: the owning service refuses the action as me.ahoo.wow.api.result.FrameworkCodes.LEDGER_STALE when the entry it holds was parked at another time, resolved and parked again since. Null acts on the entry it holds, whatever its parking: a retry only handles the parked streams again, so acting on the current parking loses nothing.