New keepstore s3 driver needs non-empty "region" to work with GCP
UseAWSS3v2Driver: true works with Google Cloud Storage buckets, but only if a valid AWS region like "us-east-1" is specified in the config file. The docs/comments say to leave region empty, but that causes requests to fail with a "could not find region configuration" error.
Suggest updating the driver and config docs to default to the "us-east-1" region when
Endpoint != "" && Region == "" in config, since this is a sane default to use for a non-AWS S3 service.