pom.xml
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<configuration>
<executable>true</executable>
</configuration>
<executions>
<execution>
<goals>
<goal>repackage</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>[ERROR] Failed to execute goal org.springframework.boot:spring-boot-maven-plugin:2.2.1.RELEASE:repackage (default) on project demo-common: Execution default of
goal org.springframework.boot:spring-boot-maven-plugin:2.2.1.RELEASE:repackage failed: Unable to find main class -> [Help 1]
[ERROR]
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR]
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/PluginExecutionException
[ERROR]
[ERROR] After correcting the problems, you can resume the build with the command
[ERROR] mvn <goals> -rf :demo-common
错误原因就是没有找到main方法，整个demo-common没有启动入口。
但是它作为核心依赖jar包，又没有参与业务，所以没有给它提供main方法的启动类。
解决办法：
去掉当前项目pom中的spring-boot-maven-plugin插件
spring-boot-maven-plugin用于给jar将依赖的第三方jar打包到当前jar中