[shunping]

Part of #40569

Problem

Since GcsUtil V2 (java-storage) became the default (#40713), Java GCS ignores GOOGLE_CLOUD_UNIVERSE_DOMAIN. Unlike the Google API client used by GcsUtil V1 (and by the Dataflow client, #40672), java-storage only takes the universe domain from StorageOptions#setUniverseDomain. Without --gcsEndpoint, every request goes to storage.googleapis.com, even with credentials for another universe.
On Trusted Partner Cloud this fails right at pipeline construction:

Error constructing default value for gcpTempLocation: tempLocation is not a valid GCS path, gs://...
...
401 Unauthorized
GET https://storage.googleapis.com/storage/v1/b/<bucket>?fields=name&projection=full

Fix

When --gcsEndpoint is not set, GcsUtilV2 resolves the universe domain and sets it on StorageOptions:

1. GOOGLE_CLOUD_UNIVERSE_DOMAIN, if set; otherwise
2. the credentials' universe domain.
   If neither is set, or the value is googleapis.com, nothing changes. An explicit --gcsEndpoint still takes precedence. This mirrors the Python fix ([Python] Fix GCS client creation in non-default universes #40674).

[github-actions]

📋 Review Summary

This PR resolves an issue in GcsUtilV2 where non-default universe domains (such as Trusted Partner Cloud) were ignored when --gcsEndpoint was not explicitly configured. It properly resolves the universe domain from GOOGLE_CLOUD_UNIVERSE_DOMAIN or the configured Credentials and applies it to StorageOptions, while preserving --gcsEndpoint precedence and default googleapis.com behavior.

🔍 General Feedback

• The resolution precedence (--gcsEndpoint > GOOGLE_CLOUD_UNIVERSE_DOMAIN > Credentials#getUniverseDomain() > default) is clean and consistent with the Google API client library behavior and the Python SDK implementation (#40674).
• Unit tests in GcsUtilV2Test thoroughly cover environment variable precedence, credential fallback, default universe handling, error handling on getUniverseDomain(), and --gcsEndpoint override.

---

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[github-actions]

Assigning reviewers:

R: @damccorm for label java.
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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 0.00%. Comparing base (a8d6afd) to head (357619d).
⚠️ Report is 75 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff             @@
##           master   #40796       +/-   ##
===========================================
- Coverage   80.04%        0   -80.05%     
===========================================
  Files         490        0      -490     
  Lines       82916        0    -82916     
===========================================
- Hits        66373        0    -66373     
+ Misses      16543        0    -16543     

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