I have lots of Objects already stored in GCS. Now I want to get their MD5 hashes that GCS has already calculated, from my Google App Engine application using the Google Cloud Storage Client Library, but I can't find anything that exposes it.
I know that the ETag contains the MD5 in the XML api for backwards compatibility, but it says don't rely on that being there for any other APIs.
I know that I can get to them with the JSON api, but I don't want to write up all that HTTPClient and Auth code and JSON parsing to get to a single attribute.
I know I can also calculate the MD5 at upload time but these files are already uploaded, and reading them all again to just calculate the MD5 seems wasteful.