[Enhancement]: Update S3 Go code examples to use feature/s3/transfermanager instead of deprecated feature/s3/manager

Background story

The AWS SDK for Go v2 has officially deprecated the feature/s3/manager package as of February 2026, replacing it with the new feature/s3/transfermanager. Currently, many code examples in the aws-doc-sdk-examples repository still use the deprecated manager package, which means developers following these examples are building applications with deprecated APIs.

What does this example accomplish?

The examples should show developers how to migrate from the deprecated feature/s3/manager to feature/s3/transfermanager with clear, production-ready patterns.

Which AWS service(s)?

Amazon S3 (Simple Storage Service)

Which AWS SDKs or tools?

• All languages
• .NET
• C++
• Go (v2)
• Java
• Java (v2)
• JavaScript
• JavaScript (v3)
• Kotlin
• PHP
• Python
• Ruby
• Rust
• Swift
• Not applicable

Are there existing code examples to leverage?

Yes, the current examples at gov2/s3/actions/bucket_basics.go provide a foundation, specifically the UploadLargeObject and DownloadLargeObject methods. However, these use the deprecated manager package. The new transfermanager package requires significant refactoring:

• Different import path: github.com/aws/aws-sdk-go-v2/feature/s3/transfermanager
• Single client type: transfermanager.Client instead of separate Uploader/Downloader
• Different method signatures: UploadObject/DownloadObject instead of Upload/Download

Do you have any reference code?

No But I'm willing to help contribute to this documentation update. I can assist with writing the updated code examples for the `bucket_basics.go` file and other relevant S3 example files that use the deprecated manager package. Please let me know how I can contribute to this effort, whether through submitting a PR with the updated code or helping review the documentation changes.