in flink-connector-gcp-pubsub/src/main/java/org/apache/flink/streaming/connectors/gcp/pubsub/PubSubSink.java [181:190]
public void invoke(IN message, SinkFunction.Context context) {
PubsubMessage pubsubMessage =
PubsubMessage.newBuilder()
.setData(ByteString.copyFrom(serializationSchema.serialize(message)))
.build();
ApiFuture<String> future = publisher.publish(pubsubMessage);
numPendingFutures.incrementAndGet();
ApiFutures.addCallback(future, failureHandler, directExecutor());
}