Github user StephanEwen commented on the issue:
https://github.com/apache/flink/pull/5928
In Flink 1.5, all checkpoints are externalized. There is no notion of
externalized checkpoints any more, just a setting to configure the retention
(retain on cancel, retain on fail, never retain).
The `state.checkpoints.dir` is the recommended option for the directory
where checkpoints are stored (and `state.backend.fs.checkpointdir` is a
deprecated key for the same setting).---
