feat(gax): add progress listener models and UploadProgressTracker

[whowes]

Introduces ResumableUploadStatus, UploadProgressListener, and thread-safe UploadProgressTracker. Tracks uploaded byte counts and state transitions across chunk attempts.

[gemini-code-assist]

Code Review

This pull request introduces a thread-safe progress tracking mechanism for resumable uploads, consisting of the ResumableUploadProgressListener interface, the ResumableUploadStatus value class, and the UploadProgressTracker coordinator, along with comprehensive unit tests. Feedback on the changes suggests clearing the registered listeners list in UploadProgressTracker once a terminal state is reached to prevent potential memory leaks.

[gemini-code-assist]

To prevent potential memory leaks and unnecessary resource retention, the list of registered listeners should be cleared once the tracker enters a terminal state (FINALIZED or FAILED). Since no further progress updates can occur after reaching a terminal state, holding onto the listeners (and potentially their enclosing classes or executors) is unnecessary.

  @GuardedBy("lock")
  private List<RegisteredListener> updateStatusLocked(ResumableUploadStatus newStatus) {
    this.currentStatus = newStatus;
    if (newStatus.getUploadUrl() != null && this.uploadSessionUrl == null) {
      this.uploadSessionUrl = newStatus.getUploadUrl();
    }
    List<RegisteredListener> snapshot = new ArrayList<>(this.listeners);
    if (newStatus.isTerminal()) {
      this.listeners.clear();
    }
    return snapshot;
  }

[sonarqubecloud]

Quality Gate failed for 'gapic-generator-java-root'

Failed conditions
76.5% Coverage on New Code (required ≥ 80%)

See analysis details on SonarQube Cloud

[sonarqubecloud]

Quality Gate failed for 'gapic-generator-java-root'

Failed conditions
0.0% Coverage on New Code (required ≥ 80%)

See analysis details on SonarQube Cloud