in flink-connector-gcp-pubsub/src/main/java/org/apache/flink/streaming/connectors/gcp/pubsub/PubSubSource.java [375:378]
public <OUT> ProjectNameBuilder<OUT> withDeserializationSchema(
PubSubDeserializationSchema<OUT> deserializationSchema) {
return new PubSubSourceBuilder<>(deserializationSchema);
}