This ticket was originally intended to track the issue reported by chun. Since I did not discover the root cause for that issue, but clarified the contract of DrillFileSystem and enforced it, I am repurposing this ticket to track the improvements to Drill FileSystem. I've moved the original FileNotFoundException issue to this ticket now https://issues.apache.org/jira/browse/DRILL-6609 .
This ticket now focuses on enforcing the immutability of the DrillFileSystem. And removes usages of fs.default.name which is now deprecated.