$ mvn clean validate                                                                                                                                                                                                                         
[INFO] Scanning for projects...
[WARNING] 
[WARNING] Some problems were encountered while building the effective model for org.wildfly:wildfly-ejb3:jar:35.0.0.Final-SNAPSHOT
[WARNING] 'dependencies.dependency.(groupId:artifactId:type:classifier)' must be unique: org.wildfly.core:wildfly-subsystem:jar -> duplicate declaration of version (?) @ line 168, column 21
[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.
[WARNING]