A policy that specifies how Cloud Pub/Sub retries message delivery.
Retry delay will be exponential based on provided minimum and maximum
backoffs. https://en.wikipedia.org/wiki/Exponential_backoff.
RetryPolicy will be triggered on NACKs or acknowledgement deadline
exceeded events for a given message. Retry Policy is implemented on a
best effort basis. At times, the delay between consecutive deliveries
may not match the configuration. That is, delay can be more or less
than configured backoff.
The maximum delay between consecutive deliveries of a given
message. Value should be between 0 and 600 seconds. Defaults
to 600 seconds.
