JBAS018754: Unexpected content of type 'element start', name is 'exclude-subsystems', text is: 'null' in JBoss EAP 6

Issue

• I'm getting this error trying to deploy my jaxws-annotations.ear containing a jaxws-annotations.war and jboss-deployment-structure.xml which is excluding the webservices subsystem.

14:34:47,902 ERROR [org.jboss.msc.service.fail] (MSC service thread 1-7) MSC000001: Failed to start service jboss.deployment.unit."jaxws-annotations.ear".STRUCTURE: org.jboss.msc.service.StartException in service jboss.deployment.unit."jaxws-annotations.ear".STRUCTURE: JBAS018733: Failed to process phase STRUCTURE of deployment "jaxws-annotations.ear"
    at org.jboss.as.server.deployment.DeploymentUnitPhaseService.start(DeploymentUnitPhaseService.java:123) [jboss-as-server-7.1.2.Final-redhat-1.jar:7.1.2.Final-redhat-1]
    at org.jboss.msc.service.ServiceControllerImpl$StartTask.startService(ServiceControllerImpl.java:1811) [jboss-msc-1.0.2.GA-redhat-1.jar:1.0.2.GA-redhat-1]
...
Caused by: javax.xml.stream.XMLStreamException: ParseError at [row,col]:[4,6]
Message: JBAS018754: Unexpected content of type 'element start', name is 'exclude-subsystems', text is: 'null'
    at org.jboss.as.server.deployment.module.descriptor.JBossDeploymentStructureParser11.unexpectedContent(JBossDeploymentStructureParser11.java:1092) [jboss-as-server-7.1.2.Final-redhat-1.jar:7.1.2.Final-redhat-1]
    at org.jboss.as.server.deployment.module.descriptor.JBossDeploymentStructureParser11.parseModuleStructureSpec(JBossDeploymentStructureParser11.java:334) [jboss-as-server-7.1.2.Final-redhat-1.jar:7.1.2.Final-redhat-1]
...

My jboss-deployment-structure.xml is pacakging in the ear/META-INF containing:

<jboss-deployment-structure>
  <sub-deployment name="jaxws-annotations.war">
     <exclude-subsystems>
        <subsystem name="webservices"/>
    </exclude-subsystems>
    <dependencies>
    </dependencies>
  </sub-deployment>
</jboss-deployment-structure>