docs(pubsub): Create a Cloud Pub/Sub sample for publishing with hedging

[michaelpri10]

This also bumps the samples libraries-bom version

[snippet-bot]

Here is the summary of changes.

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• java-pubsub/samples/snippets/src/main/java/pubsub/PublishWithHedgingSettingsExample.java:19, tag pubsub_publish_hedging_settings

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[gemini-code-assist]

Code Review

This pull request updates the libraries-bom dependency version to 26.90.0 and introduces a new sample snippet, PublishWithHedgingSettingsExample.java, which demonstrates how to publish Pub/Sub messages with custom hedging settings. It also adds a corresponding integration test in PublisherIT.java. Feedback on the changes suggests refactoring the resource management of the Publisher instance to use a try-with-resources block for cleaner and safer resource handling, as well as using a double instead of a float for the refillRatio setting to avoid implicit widening.

[gemini-code-assist]

Using try-with-resources is the modern, idiomatic Java way to manage resources. Since Publisher implements AutoCloseable (via BackgroundResource), its close() method automatically handles shutdown() and awaitTermination(). Refactoring this to use try-with-resources reduces boilerplate and ensures the publisher is safely closed. Additionally, HedgingSettings.Builder#setRefillRatio expects a double parameter, so we can use double directly instead of float to avoid implicit widening.

    // Hedging settings configures how and when the publisher sends multiple concurrent publish
    // requests to reduce tail latency.
    Duration hedgeDelay = Duration.ofMillis(500); // default: 1000 ms (1 second)
    int maxTokens = 100; // default: 50
    double refillRatio = 0.05; // default: 0.1

    HedgingSettings hedgingSettings =
        HedgingSettings.newBuilder()
            .setHedgeDelay(hedgeDelay)
            .setMaxTokens(maxTokens)
            .setRefillRatio(refillRatio)
            .build();

    // Create a publisher instance with hedging settings bound to the topic
    try (Publisher publisher =
        Publisher.newBuilder(topicName).setHedgingSettings(hedgingSettings).build()) {

      String message = "Hello world!";
      ByteString data = ByteString.copyFromUtf8(message);
      PubsubMessage pubsubMessage = PubsubMessage.newBuilder().setData(data).build();

      // Once published, returns a server-assigned message id (unique within the topic)
      ApiFuture<String> messageIdFuture = publisher.publish(pubsubMessage);
      String messageId = messageIdFuture.get();
      System.out.println("Published a message with hedging settings: " + messageId);
    }