hdi_isfolder shall always be set in lower case on backend

[vibhansa-msft]

Description

Customer ICM
Duplicate Hdi_isfolder keys in metadata of directories on HNS account.

• Feature / Bug Fix:
  When azcopy retreives properties from backend, Hdi_isfolder is camel cased by Golang. Later code (in case of account to account copy or sync) reuses the same and we end up adding "Hdi" in camel case while setting the properties on destination. When backend returns back the ListBlob API responce it add "hdi_isfolder" for all directories (all in lower case). This creates a duplicate key in metadata ("hdi" and "Hdi", one set by azcopy during sync and one added by backend during list on dfs account).

• Related Links:
  ICM

Type of Change

• Bug fix
• New feature
• Documentation update required
• Code quality improvement
• Other (describe):

How Has This Been Tested?

This needs manual validation

[Copilot]

Pull request overview

This PR fixes a bug where duplicate hdi_isfolder metadata keys were being created on HNS (Hierarchical Namespace Storage) accounts. The issue occurred because Go canonicalizes the key as "Hdi_isfolder" when retrieving properties, but the backend always returns "hdi_isfolder" in lowercase during ListBlob API responses. During account-to-account copy or sync operations, AzCopy would set the camel-cased version, while the backend would also add the lowercase version, resulting in duplicate keys.

Key Changes:

• Normalized hdi_isfolder metadata key to always be set in lowercase on the backend
• Removed conditional logic that could set either "Hdi_isfolder" or "hdi_isfolder"
• Ensured the camel-cased variant is deleted before setting the lowercase version

---

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[vibhansa-msft]

az storage blob list --account-name vikasfusename --container-name testcntgo1 --auth-mode login --include m --prefix "abcd"
....
When hdi_isfolder is set by azcopy
"name": "abcd",
"objectReplicationDestinationPolicy": null,
"objectReplicationSourceProperties": [],
"metadata": {
"hdi_isfolder": "true"
},
.....
When Hdi_isfolder is set by azcopy
"name": "abcd",
"metadata": {
"Hdi_isfolder": "true",
"hdi_isfolder": "true"
},
......

[gapra-msft]

we should apply this to is_symlink too

[vibhansa-msft]

While copying symlinks we are creating the metadata with all lower case explicitly:

func (s *blobSymlinkSender) SendSymlink(linkData string) error {
	err := s.getExtraProperties()
	if err != nil {
		return fmt.Errorf("when getting additional folder properties: %w", err)
	}
	s.metadataToApply["is_symlink"] = to.Ptr("true")

[vibhansa-msft]

In case of blob to blob copy with preserve-symlink flags here is my output:

   GET https://vikasfuseblob.blob.core.windows.net/testcntgo1/abcd%2Fa.lnk?...
   Accept: application/xml
   User-Agent: AzCopy/10.32.0~preview.1 azsdk-go-azblob/v1.6.2 (go1.25.1; linux)
   X-Ms-Client-Request-Id: 9602ecc6-11c6-468a-6ec4-373ccafae6e3
   x-ms-version: 2025-07-05
   --------------------------------------------------------------------------------
   RESPONSE Status: 200 OK
   ...
   X-Ms-Lease-Status: unlocked
   X-Ms-Meta-Is_symlink: true
   ...
  --------------------------------------------------------------------------------
   PUT https://vikasfusename.blob.core.windows.net/testcntgo1/abcd%2Fa.lnk?...
  ...
   x-ms-blob-type: BlockBlob
   x-ms-meta-is_symlink: true
   x-ms-version: 2025-07-05
  ...