Pub/Sub target. The job will be delivered by publishing a message to
the given Pub/Sub topic.
.. attribute:: topic_name
Required. The name of the Cloud Pub/Sub topic to which
messages will be published when a job is delivered. The topic
name must be in the same format as required by PubSub's
PublishRequest.name <https://cloud.google.com/pubsub/docs/ref
erence/rpc/google.pubsub.v1#publishrequest>__, for example
projects/PROJECT_ID/topics/TOPIC_ID. The topic must be in
the same project as the Cloud Scheduler job.
Attributes for PubsubMessage. Pubsub message must contain
either non-empty data, or at least one attribute.
