You're seeing just the function set_blob_properties, go back to ExMicrosoftAzureStorage.Storage.Blob module for more information.
Link to this function

set_blob_properties(blob, blob_properties)

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Sets blob properties.

Follows the same behaviour as the underlying REST API where setting one property will also implicitly set others to nil, unless you explitly set them in this request.

See https://docs.microsoft.com/en-us/rest/api/storageservices/set-blob-properties