chore(pubsub): migrate java-pubsub to monorepo

[meltsufin]

Using script from here: #12962.

[gemini-code-assist]

Code Review

This pull request adds support for the Google Cloud Pub/Sub Java client library, including configuration, documentation, and necessary infrastructure files. My review identified several issues: the Publisher class incorrectly handles thread interruptions, the Waiter class has a thread-safety issue with its pendingCount() method, the LoggingUtil class should be made fully static, and there are missing imports in the provided code snippets for TimeUnit.

[gemini-code-assist]

This block catches InterruptedException but does not restore the interrupt status or exit the loop. While CountDownLatch.await() clears the interrupt status when throwing, ignoring the interruption prevents the thread from being shut down correctly by its owner. Since this method's signature does not allow throwing InterruptedException, it is better to use Uninterruptibles.awaitUninterruptibly to handle the wait correctly while preserving the interrupt status for the caller.

          com.google.common.util.concurrent.Uninterruptibles.awaitUninterruptibly(messageWaiter);

[gemini-code-assist]

Similar to the message waiter above, this block swallows InterruptedException. Use Uninterruptibles.awaitUninterruptibly to ensure the interrupt status is correctly managed without breaking the method signature.

          com.google.common.util.concurrent.Uninterruptibles.awaitUninterruptibly(bytesWaiter);

[gemini-code-assist]

The pendingCount() method accesses the pendingCount field without synchronization. Since this field is modified within synchronized blocks in other methods, this read is not thread-safe and may return stale values due to lack of visibility guarantees. This method should be marked as synchronized to ensure thread-safety for shared state.

Suggested change

	public int pendingCount() {
	return pendingCount;
	}
	public synchronized int pendingCount() {
	return pendingCount;
	}

References

1. Ensure that counters or state accessed concurrently by multiple threads are thread-safe, either by using Atomic types or by protecting access with synchronization/locks.

[gemini-code-assist]

This class is designed as a utility class with static loggers and methods that do not use instance state. It should have a private constructor to prevent instantiation, and its methods should ideally be made static to reflect its stateless nature.

[gemini-code-assist]

The code snippet for publishing messages uses TimeUnit.MINUTES in the finally block (line 55), but the java.util.concurrent.TimeUnit import is missing from the snippet's import section.

  import com.google.api.core.ApiFuture;
  import com.google.api.core.ApiFutureCallback;
  import com.google.api.core.ApiFutures;
  import com.google.cloud.pubsub.v1.Publisher;
  import com.google.common.util.concurrent.MoreExecutors;
  import com.google.protobuf.ByteString;
  import com.google.pubsub.v1.PubsubMessage;
  import java.util.concurrent.TimeUnit;

[gemini-code-assist]

The code snippet for publishing messages is missing the import for java.util.concurrent.TimeUnit, which is required for the awaitTermination call on line 156.

Suggested change

	import com.google.api.core.ApiFuture;
	import com.google.api.core.ApiFutureCallback;
	import com.google.api.core.ApiFutures;
	import com.google.cloud.pubsub.v1.Publisher;
	import com.google.common.util.concurrent.MoreExecutors;
	import com.google.protobuf.ByteString;
	import com.google.pubsub.v1.PubsubMessage;
	import com.google.api.core.ApiFuture;
	import com.google.api.core.ApiFutureCallback;
	import com.google.api.core.ApiFutures;
	import com.google.cloud.pubsub.v1.Publisher;
	import com.google.common.util.concurrent.MoreExecutors;
	import com.google.protobuf.ByteString;
	import com.google.pubsub.v1.PubsubMessage;
	import java.util.concurrent.TimeUnit;