fs.s3a.authoritative.path currently requires a qualified URI (e.g. s3a://bucket/path) which is how I see this being used most immediately, but it also make sense for someone to just be able to configure /path, if all of their buckets follow that pattern, or if they're providing configuration already in a bucket-specific context (e.g. job-level configs, etc.) Just need to qualify whatever is passed in to allowAuthoritative to make that work.
HADOOP-16396 Gabor pointed out a few whitepace nits that I neglected to fix before merging.