Duplicated in the reactor problem when executing the mvn command

In the maven combined project, run mvn clean and report the following error:

 

 

[INFO] Scanning for projects...

[INFO] ------------------------------------------------------------------------
[ERROR] BUILD FAILURE
[INFO] ------------------------------------------------------------------------

[INFO] Project 'xx' is duplicated in the reactor

 

The reason is that the parent pom.xml specifies A, B, and C as sub-modules, and the pom of sub-module A specifies B and C as its own sub-modules, resulting in a conflict. Just delete the subModules specified in the parent pom.

In addition, dependencies only need to be defined once by the parent or child pom. Do not repeat definitions.