internal void Populate(IDictionary<string, string> requestHeaders)
{
foreach(var entry in _metadata)
requestHeaders.Add(entry.Key, entry.Value.ToString());
if (!requestHeaders.ContainsKey(HttpHeaders.ContentType))
requestHeaders.Add(HttpHeaders.ContentType, HttpUtils.DefaultContentType);
foreach(var entry in _userMetadata)
requestHeaders.Add(OssHeaders.OssUserMetaPrefix + entry.Key, entry.Value);
}