这是一个比较不应该犯的错误了（我自己犯的）。CMD命令行操作的时候，在执行最开始有如下显示：
[INFO] Scanning for projects…
[WARNING]
[WARNING] Some problems were encountered while building the effective model for com.manning:readinglist:jar:0.0.1-SNAPSHOT
[WARNING] ‘build.plugins.plugin.(groupId:artifactId)’ must be unique but found duplicate declaration of plugin org.springframework.boot:spring-boot-maven-plugin @ line 70, column 12
[WARNING]
[WARNING] It is highly recommended to fix these problems because they threaten the stability of your build.
[WARNING]
[WARNING] For this reason, future Maven versions might no longer support building such malformed projects.
这是因为build.plugins.plugin.(groupId:artifactId)重复配置。在刚开始学的时候，搜了不少博文，所以不小心重复配置了org.springframework.boot:spring-boot-maven-plugin。
之所以出现这个问题是因为在项目构建的时候，已经有了一个org.springframework.boot:spring-boot-maven-plugin配置，而我在排查问题的时候没有注意到，按照别人的操作提示又重新构建了一个org.springframework.boot:spring-boot-maven-plugin。