GCS client library migration in Java SDK - part 2

[shunping]

This is the second part of GCS client library migration for most of the blob/bucket metadata manipulation methods. A parameterized test suite is also added to make sure the behavior of GcsUtil V2 is consistent with V1 as much as it could be.

Objects/Blobs:

• fileSize()
• getObject() (deprecated and the new api is getBlob())
• getObjects() (deprecated and the new api is getBlobs())
• listObjects() (deprecated and the new api is listBlobs())
• expand()

Buckets:

• getBucket() (deprecated and the new api is getBucketWithOptions()
• bucketAccessible()
• verifyBucketAccessible()
• bucketOwner()
• createBucket()
• removeBucket()

---

Notice that:

• Three other metadata related methods (batch copy, move and delete blobs) will be included in a follow-up PR.
• Everything is guarded with an feature flag which is disabled by default.

[shunping]

R: @Abacn

[Abacn]

/gemini review

[gemini-code-assist]

Code Review

This pull request is a significant step in migrating the GCS client library to the newer version. The approach of using a feature flag and a facade (GcsUtil) to delegate to either the V1 or V2 implementation is sound and allows for a safe, gradual migration. The addition of parameterized integration tests to ensure behavioral consistency between the two versions is excellent.

I have identified a critical bug in the batch getBlobs implementation that could lead to incorrect error messages. Additionally, I've found an opportunity to improve the efficiency and atomicity of the removeBucket method. There's also a minor, but repeated, typo in error messages across several new methods. Addressing these points will further improve the quality of this contribution.

[github-actions]

Assigning reviewers:

R: @Abacn for label java.
R: @Abacn for label build.

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[Abacn]

Thanks!