这个错误通常是下载了子项目，没有把父项目下载下来。
子项目要依赖父项目的pom
The relative path of the parent pom.xml file within the check out. If not specified, it defaults to ../pom.xml. Maven looks for the parent
POM first in this location on the filesystem, then the local repository, and lastly in the remote repo. relativePath allows you to select a
different location, for example when your structure is flat, or deeper without an intermediate parent POM. However, the group ID, artifact ID
and version are still required, and must match the file in the location given or it will revert to the repository for the POM. This feature
is only for enhancing the development in a local checkout of that project. Set the value to an empty string in case you want to disable the
feature and always resolve the parent POM from the repositories. Default value is: ../pom.xml.
所以只要把父pom.xml放到各个子项目的上一级就可以了
The relative path of the parent pom.xml file within the check out. If not specified, it defaults to ../pom.xml. Maven looks for the parent POM first in this location on the filesystem, then the local repository, and lastly in the remote repo. relativePath allows you to select a different location, for example when your structure is flat, or deeper without an intermediate parent POM. However, the group ID, artifact ID and version are still required, and must match the file in the location given or it will revert to the repository for the POM. This feature is only for enhancing the development in a local checkout of that project. Set the value to an empty string in case you want to disable the feature and always resolve the parent POM from the repositories.
Default value is: ../pom.xml.