我正在使用以下代码将文件上传到blob存储。对于给定的文件，我想设置过期时间。之后，系统将自动删除文件。

[HttpPost("UploadFile")]
public async Task<IActionResult> UploadFile([FromForm] IFormFile file)
{
    if (file == null || file.Length <= 0)
        return BadRequest("File is required.");

    try
    {
        // Create a unique filename to avoid conflicts
        string fileName = Guid.NewGuid().ToString() + "_" + file.FileName;

        // Upload the file to Azure Blob Storage
        BlobServiceClient blobServiceClient = new BlobServiceClient(_connectionString);
        BlobContainerClient containerClient = blobServiceClient.GetBlobContainerClient(_containerName);
        BlobClient blobClient = containerClient.GetBlobClient(fileName);

        using (var stream = file.OpenReadStream())
        {
            await blobClient.UploadAsync(stream, overwrite: true);
        }

        // Set the retention policy for the blob (30 days)
        var metadata = new Dictionary<string, string>
        {
            { "retention-days", "30" }
        };

        await blobClient.SetMetadataAsync(metadata);

        return Ok("File uploaded successfully.");
    }
    catch (Exception ex)
    {
        return StatusCode(500, $"An error occurred: {ex.Message}");
    }
}

字符串
有了这个代码，我可以上传文件，但在设置保留期时出现错误“The metadata specified is invalid. It has characters that are not permitted”。
我也试过这段代码，但得到了同样的错误：

BlobProperties properties = await blobClient.GetPropertiesAsync();
            properties.Metadata.Add("retention-days", "30");
            await blobClient.SetMetadataAsync(properties.Metadata);

型

如何确保在X天后能够删除azure blob存储中的文件？