Spring Boot version 2.2.0.M6 change the value of `spring.messages.basename` in `application.properties` does not make any difference [demo.zip](https://github.com/spring-projects/spring-boot/files/3670460/demo.zip) In this demo,the test `com.example.demo.DemoApplicationTests#contextLoads` will always fail. Make a breakpoint at `resolveCodeWithoutArguments:151, org.springframework.context.support.ResourceBundleMessageSource#resolveCodeWithoutArguments` The `getBasenameSet()` will always return a set which only contain one element: "messages" But if eval the `getResourceBundle("msg", locale)` at that point,it will return the correct thing. Also `org.springframework.boot.autoconfigure.context.MessageSourceAutoConfiguration.ResourceBundleCondition#getResources` returns the correct thing.