Make StorageWriteChannel public, or provide a way to get the upload response metadata from a WriteChannel #3482
Description
Is your feature request related to a problem? Please describe.
When using a WriteChannel to upload files to Cloud Storage, there's no way to get the response metadata (BlobInfo) directly.
This can be useful to get etag, md5, etc.
The information is acutally exposed in StorageWriteChannel.getObject(), but the interface is not public.
Describe the solution you'd like
Make StorageWriteChannel public, or expose another way of getting the metadata of the uploaded file.
Describe alternatives you've considered
Perform an additional get request after uploading the file.
But there's no guarantee that the retrieved version is the same as the one just uploaded (in case of concurrent services writing the same file).