OnTimeout 
    data class OnTimeout(val duration: Duration, val flowStatus: FlowStatus = FlowStatus.Unknown) : CleanupPolicy
Apply cleanup if a flow stays open beyond a specified time.
This API does not guarantee immediate cleanup as soon as the timeout expires — the event becomes eligible for cleanup after the duration has passed, and the actual cleanup may occur later.
Parameters
duration
Duration after flow start for it to become eligible for cleanup.