1. spring.cloud.vault.kv.application-name=no-such-app (nothing stored at secret/no-such-app), fail-fast off:
   started: yes; db.password = null
   vault property sources mounted: [secret/no-such-app, secret/application]
2. same, spring.cloud.vault.fail-fast=true:
   started: yes; db.password = null
3. same, with the strict profile (RequireDbPassword guard in application code):
   started: no; IllegalStateException: db.password is not configured: refusing to start
4. wrong token, fail-fast off (the default):
   started: yes; db.password = null
   wrong token, fail-fast=true:
   started: no; Forbidden: 403 Forbidden on GET request for "http://localhost:<port>/v1/secret/secrets-demo": "{"errors":["2 errors occurred:\n\t* permission denied\n\t* invalid token\n\n"]}<EOL>"
5. Vault unreachable (127.0.0.1:1), import = vault://, fail-fast off:
   started: yes; db.password = null
   Vault unreachable, fail-fast=true:
   started: no; HttpHostConnectException: Connect to http://127.0.0.1:1 failed: Connection refused (connect failed)
6. Vault unreachable, import = optional:vault://, fail-fast=true:
   started: no; HttpHostConnectException: Connect to http://127.0.0.1:1 failed: Connection refused (connect failed)