在stack overflow有人说：Your code is in the default package, i.e. you have .java files in src/main/java with no package statement at the top. There’s a warning message in the log indicating that this is likely to cause problems: ** WARNING ** : Your ApplicationContext is unlikely to start due to a @ComponentScan of the default package.

https://stackoverflow.com/questions/35070455/springboot-beandefinitionstoreexception-failed-to-parse-configuration-class

还有这里也是这样说：
https://better-coding.com/solved-spring-boot-your-applicationcontext-is-unlikely-to-start-due-to-a-componentscan-of-the-default-package/

我把Application.java丢到包里面了，就到这个注释@ComponentScan报错了，就算去掉括号的内容也不行。