in flink-connector-gcp-pubsub/src/main/java/org/apache/flink/streaming/connectors/gcp/pubsub/PubSubSource.java [309:318]
public PubSubSourceBuilder<OUT> withPubSubSubscriberFactory(
int maxMessagesPerPull, Duration perRequestTimeout, int retries) {
this.pubSubSubscriberFactory =
new DefaultPubSubSubscriberFactory(
ProjectSubscriptionName.format(projectName, subscriptionName),
retries,
perRequestTimeout,
maxMessagesPerPull);
return this;
}