dead
A policy that specifies the conditions for dead lettering messages in this subscription. If dead_letter_policy is not set, dead lettering is disabled. The Cloud Pub/Sub service account associated with this subscription's parent project (i.e., service-{project_number}@gcp-sa-pubsub.iam.gserviceaccount.com) must have permission to Acknowledge() messages on this subscription. Structure is documented below.