maven packge（maven打包问题）

- When creating a Spring Boot project, the server Url will report when using Alibaba Cloud's packaging: if there is no main list attribute, using the default one will not

- 创建 Spring Boot 项目的时候，Server Url 使用阿里云的打包就会报：没有主清单属性，使用默认的就不会

Start by reproducing the issue while creating a Spring Boot project with the Server Url set to Alibaba Cloud, comparing Alibaba Cloud packaging with the default packaging. Trace the generated package and verify that the Alibaba Cloud variant includes the required main manifest attribute without changing the default variant's behavior.

Written by the indexing model from the issue text.