When application.xml and application.yaml exist in the configuration file， the startup fails。
When the application.xml is changed to another name or moved to another directory, the startup is successful。
Found when I use @ImportResource to import xml bean，But even if you don't use it, you will still get an error
case: spring-xml-demo.zip
Comment From: wilkinsona
This is the expected behaviour. Spring Boot supports properties files in both .properties and .xml format. As a result, your application.xml file that is in one of the locations which Spring Boot checks for configuration properties is being loaded as an XML properties file.