BootstrapConfigFileApplicationListener cant handle optional config locations

[larsgrefer]

Describe the bug

BootstrapConfigFileApplicationListener can't handle spring.config.additional-locations with optional: prefixes.

When setting spring.config.additional-location to optional:file:/foo or optional:/bar, https://github.com/spring-cloud/spring-cloud-commons/blob/1a387e1e39d3ce5f2b6a32668eb8ede9e24154d4/spring-cloud-context/src/main/java/org/springframework/cloud/bootstrap/BootstrapConfigFileApplicationListener.java#L701-L718 will turn these locations into file:optional:file:/foo and file:optional:/bar.

The following code will then decide that the Resource file:optional:file:/foo/application.properties does not exist, (while file:/foo/application.properties would exist) https://github.com/spring-cloud/spring-cloud-commons/blob/1a387e1e39d3ce5f2b6a32668eb8ede9e24154d4/spring-cloud-context/src/main/java/org/springframework/cloud/bootstrap/BootstrapConfigFileApplicationListener.java#L501-L508

This can cause ordering issues between internal and external configuration files, depending on the execution order of BootstrapConfigFileApplicationListener and ConfigDataEnvironmentPostProcessor (so #1213 will hide this problem)

When BootstrapConfigFileApplicationListener runs first, we get this order:

1. ~external properties~ (not found by spring cloud because of this bug)
2. internal properties (found by BootstrapConfigFileApplicationListener)
3. external-properties (found by ConfigDataEnvironmentPostProcessor)
4. internal properties (found by ConfigDataEnvironmentPostProcessor)

When ConfigDataEnvironmentPostProcessor runs first, we get this order:

1. external-properties (found by ConfigDataEnvironmentPostProcessor)
2. internal properties (found by ConfigDataEnvironmentPostProcessor)
3. ~external properties~ (not found by spring cloud because of this bug)
4. internal properties (found by BootstrapConfigFileApplicationListener)

In the first case, the internal properites suddenly get precedence before the external ones.

[ryanjbaxter]

But since #1213 this should no longer matter correct?

[spring-cloud-issues]

If you would like us to look at this issue, please provide the requested information. If the information is not provided within the next 7 days this issue will be closed.

[larsgrefer]

@ryanjbaxter #1213 will hide this, yes

[ryanjbaxter]

After discussing this with the team we view #1213 as a fix for the issue so this can be closed