Include the default application in the Redis backend

[HDPark95]

RedisEnvironmentRepository only reads the hashes named after the requested application (app, app-<profile>), so properties under the shared application key are never returned. The other backends include them: jdbc, mongodb, credhub, native and aws-s3.

This adds the default application keys, ordered the way jdbc and credhub do, so the requested application still wins over the shared defaults: app-p2, application-p2, app-p1, application-p1, app, application. When the requested application is application the key list is unchanged.

New test in RedisEnvironmentRepositoryIntegrationTests: on 5.0.x it fails with ["redis:myapp-prod", "redis:myapp"] and passes with the change.

Fixes gh-3134

[ryanjbaxter]

Can you submit this against the 5.0.x branch?

[ryanjbaxter]

I am pretty sure application can be null and can be comma delimated, both of which are not handled here

spring-cloud-config/spring-cloud-config-server/src/main/java/org/springframework/cloud/config/server/environment/CredhubEnvironmentRepository.java

Lines 97 to 112 in 99f4902

	private List<String> normalize(String commaDelimitedItems, String defaultItem) {
	return normalize(defaultItem + "," + commaDelimitedItems);
	}
	/**
	* Splits the comma-delimited items and returns the reversed distinct items.
	*/
	private List<String> normalize(String commaDelimitedItems) {
	var items = Arrays.stream(split(commaDelimitedItems))
	.distinct()
	.filter(StringUtils::hasText)
	.collect(Collectors.toList());
	Collections.reverse(items);
	return items;
	}

[HDPark95]

Handled in 1411856, following CredhubEnvironmentRepository#normalize: application goes through commaDelimitedListToStringArray, trimmed, filtered on hasText and de-duplicated, with application prepended. So null resolves to the shared hash only, and app1,app2 reads every listed hash with later names taking precedence, the same order the Credhub backend produces. Two integration tests cover both cases (null -> [application-prod, application]; "app1, app2,app1" -> [app2-prod, app1-prod, application-prod, app2, app1, application]). Reverting the source change fails both.

[HDPark95]

@ryanjbaxter the PR is targeting 5.0.x already (base branch 5.0.x, one commit on top). Let me know if you'd rather have it against a different branch. The null / comma-delimited handling is in 1411856, see the inline reply.