ackDeadlineSeconds property

The approximate amount of time (on a best-effort basis) Pub/Sub waits for the subscriber to acknowledge receipt before resending the message.

In the interval after the message is delivered and before it is acknowledged, it is considered to be outstanding. During that time period, the message will not be redelivered (on a best-effort basis). For pull subscriptions, this value is used as the initial value for the ack deadline. To override this value for a given message, call ModifyAckDeadline with the corresponding ack_id if using non-streaming pull or send the ack_id in a StreamingModifyAckDeadlineRequest if using streaming pull. The minimum custom deadline you can specify is 10 seconds. The maximum custom deadline you can specify is 600 seconds (10 minutes). If this parameter is 0, a default value of 10 seconds is used. For push delivery, this value is also used to set the request timeout for the call to the push endpoint. If the subscriber never acknowledges the message, the Pub/Sub system will eventually redeliver the message.

Optional.