// MINIO_KMS_SECRET_KEY_FILE. The docker image always sets the
	// MINIO_KMS_SECRET_KEY_FILE - either to the argument passed to
	// the container or to a default string (e.g. "minio_master_key").
	//
	// We have to distinguish a explicit config from an implicit. Hence,
	// we unset the env. vars if they are set but empty or contain a path
	// which does not exist. The downside of this check is that if