Document property source precendence using spring.config.import defined in application.yml vs adding as -Dspring.config.import

Describe the bug
When we add spring.config.import in application.yml of an application's src/main/resources vs the same property is added as -D parameter during the start up of the application, the behavior changes in terms of property order.

Sample
A test case is added namely ServerMyTestApplicationTests under spring-cloud-config/spring-cloud-config-sample/src/test/java (https://github.com/nagsuchandra/spring-cloud-config.git) and it's method contextLoads shows the issue. There is documentation added to the source file .

Error case:
application.yml has the following

spring:
  cloud:
    config:
      uri: http://localhost:${config.port:8888}
  config:
    import: configserver:${spring.cloud.config.uri}

Now if we run the test ServerMyTestApplicationTests.contextLoads, the property sources are as follows.

• Config resource 'class path resource [application-baz.yml]' via location 'optional:classpath:/':{key=jarlocal-app-baz-yml}
• configserver:file:././target/repos/configmytest-repo//payroll-baz.yml:{key=remote-payroll-baz-yml}
• configserver:file:././target/repos/configmytest-repo//application-baz.yml:{key=remote-app-baz-yml}
• configserver:file:././target/repos/configmytest-repo//payroll.yml:{key=remote-payroll-yml}
• configserver:file:././target/repos/configmytest-repo//application.yml:{info.foo=bar}
• Config resource 'class path resource [application.yml]' via location 'optional:classpath:/':{info.component=Config Samples, endpoints.restart.enabled=true, logging.levels.org.springframework.boot.env.PropertySourcesLoader=TRACE, logging.levels.org.springframework.web=DEBUG, spring.cloud.config.uri=http://localhost:${config.port:8888}, spring.config.import=configserver:${spring.cloud.config.uri}}

application.yml does NOT have the spring.config.import in there and -Dspring.config.import is passed in

• configserver:file:././target/repos/configmytest-repo//payroll-baz.yml:{key=remote-payroll-baz-yml}
• configserver:file:././target/repos/configmytest-repo//application-baz.yml:{key=remote-app-baz-yml}
• configserver:file:././target/repos/configmytest-repo//payroll.yml:{key=remote-payroll-yml}
• configserver:file:././target/repos/configmytest-repo//application.yml:{info.foo=bar}
• Config resource 'class path resource [application-baz.yml]' via location 'optional:classpath:/':{key=jarlocal-app-baz-yml}
• Config resource 'class path resource [application.yml]' via location 'optional:classpath:/':{info.component=Config Samples, endpoints.restart.enabled=true, logging.levels.org.springframework.boot.env.PropertySourcesLoader=TRACE, logging.levels.org.springframework.web=DEBUG}

Config data files ordering gets reversed if application.yml has spring.config.import defined in it , but -D maintains the ordering in the right precedence.

1. Application properties packaged inside your jar (application.properties and YAML variants).
2. Profile-specific application properties packaged inside your jar (application-{profile}.properties and YAML variants).
3. Application properties outside of your packaged jar (application.properties and YAML variants).
4. Profile-specific application properties outside of your packaged jar (application-{profile}.properties and YAML variants). – highest priority

Start with spring-cloud-config-sample/src/test/java/ServerMyTestApplicationTests and its contextLoads method, then compare the application.yml and -Dspring.config.import cases described in the issue. Review the documented property-source ordering and update the relevant source-file documentation so the differing precedence is explained and the example accurately reflects the observed behavior.