When executing a copy
command to a storage in B2, for each chunk checks to see if it already exists in the storage, and then copies it.
TRACE BACKBLAZE_CALL [8] URL request 'HEAD https://f001.backblazeb2.com/file/[...]/chunks/90/5915...8083' returned status code 404
INFO SNAPSHOT_COPY Chunk 905915...8083 copied to the destination
The question is: which is the B2 API transaction used for this “check” if the chunk exists?