A dependency is declared twice in the root pom.xml with different parameters:

[WARNING]
[WARNING] Some problems were encountered while building the effective model for org.jboss.as:jboss-as-build:pom:7.0.0.Beta2-SNAPSHOT
[WARNING] 'dependencyManagement.dependencies.dependency.(groupId:artifactId:type:classifier)' must be unique: org.apache.cxf:cxf-rt-ws-security:jar -> duplicate declaration of version ${version.org.apache.cxf} @ org.jboss.as:jboss-as-parent:7.0.0.Beta2-SNAPSHOT, /home/david/src/java/as7/jboss-as/pom.xml, line 1417, column 25
[WARNING]
[WARNING] Some problems were encountered while building the effective model for org.jboss.as:jboss-as-osgi-configadmin:bundle:7.0.0.Beta2-SNAPSHOT
[WARNING] The expression ${artifactId} is deprecated. Please use ${project.artifactId} instead.
[WARNING]
[WARNING] Some problems were encountered while building the effective model for org.jboss.as:jboss-as-parent:pom:7.0.0.Beta2-SNAPSHOT
[WARNING] 'dependencyManagement.dependencies.dependency.(groupId:artifactId:type:classifier)' must be unique: org.apache.cxf:cxf-rt-ws-security:jar -> duplicate declaration of version ${version.org.apache.cxf} @ line 1417, column 25
[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]