Cannot specify module to load vault class from in JBoss EAP 6

Issue

I am trying to configure a module with my SecurityVault library but it does not seem to load the module.

I put the class in a module called com.example.vault, and edit standalone.xml to have

<vault code="com.example.vaultMySecurityVault"/>

When starting the server, an error is producted:

ERROR [org.jboss.as.controller.management-operation] JBAS014612: Operation ("add") failed - address: ([("core-service" => "vault")]): java.lang.RuntimeException: JBAS015804: Error initializing vault --  org.jboss.as.server.services.security.VaultReaderException: org.jboss.security.vault.SecurityVaultException: PB00015: Null Value:Unable to create vault:class is null
        at org.jboss.as.server.services.security.VaultAddHandler.performRuntime(VaultAddHandler.java:115)
        at org.jboss.as.controller.AbstractAddStepHandler$1.execute(AbstractAddStepHandler.java:50) [jboss-as-controller-7.1.2.Final-redhat-1.jar:7.1.2.Final-redhat-1]
        at org.jboss.as.controller.AbstractOperationContext.executeStep(AbstractOperationContext.java:397) [jboss-as-controller-7.1.2.Final-redhat-1.jar:7.1.2.Final-redhat-1]
        at org.jboss.as.controller.AbstractOperationContext.doCompleteStep(AbstractOperationContext.java:284) [jboss-as-controller-7.1.2.Final-redhat-1.jar:7.1.2.Final-redhat-1]
        at org.jboss.as.controller.AbstractOperationContext.completeStep(AbstractOperationContext.java:211) [jboss-as-controller-7.1.2.Final-redhat-1.jar:7.1.2.Final-redhat-1]
        at org.jboss.as.controller.ParallelBootOperationStepHandler.execute(ParallelBootOperationStepHandler.java:161) [jboss-as-controller-7.1.2.Final-redhat-1.jar:7.1.2.Final-redhat-1]
        at org.jboss.as.controller.AbstractOperationContext.executeStep(AbstractOperationContext.java:397) [jboss-as-controller-7.1.2.Final-redhat-1.jar:7.1.2.Final-redhat-1]
        at org.jboss.as.controller.AbstractOperationContext.doCompleteStep(AbstractOperationContext.java:284) [jboss-as-controller-7.1.2.Final-redhat-1.jar:7.1.2.Final-redhat-1]
        at org.jboss.as.controller.AbstractOperationContext.completeStep(AbstractOperationContext.java:211) [jboss-as-controller-7.1.2.Final-redhat-1.jar:7.1.2.Final-redhat-1]
        at org.jboss.as.controller.ModelControllerImpl.boot(ModelControllerImpl.java:175) [jboss-as-controller-7.1.2.Final-redhat-1.jar:7.1.2.Final-redhat-1]
        at org.jboss.as.controller.AbstractControllerService.boot(AbstractControllerService.java:191) [jboss-as-controller-7.1.2.Final-redhat-1.jar:7.1.2.Final-redhat-1]
        at org.jboss.as.server.ServerService.boot(ServerService.java:295)
        at org.jboss.as.server.ServerService.boot(ServerService.java:270)
        at org.jboss.as.controller.AbstractControllerService$1.run(AbstractControllerService.java:156) [jboss-as-controller-7.1.2.Final-redhat-1.jar:7.1.2.Final-redhat-1]
        at java.lang.Thread.run(Thread.java:722) [rt.jar:1.7.0_09]
Caused by: org.jboss.as.server.services.security.VaultReaderException: org.jboss.security.vault.SecurityVaultException: PB00015: Null Value:Unable to create vault:class is null
        at org.jboss.as.security.vault.RuntimeVaultReader.createVault(RuntimeVaultReader.java:74)
        at org.jboss.as.server.services.security.VaultAddHandler.performRuntime(VaultAddHandler.java:113)
        ... 14 more
Caused by: org.jboss.security.vault.SecurityVaultException: PB00015: Null Value:Unable to create vault:class is null
        at org.jboss.security.vault.SecurityVaultFactory.get(SecurityVaultFactory.java:67)
        at org.jboss.as.security.vault.RuntimeVaultReader$1.run(RuntimeVaultReader.java:67)
        at org.jboss.as.security.vault.RuntimeVaultReader$1.run(RuntimeVaultReader.java:61)
        at java.security.AccessController.doPrivileged(Native Method) [rt.jar:1.7.0_09]
        at org.jboss.as.security.vault.RuntimeVaultReader.createVault(RuntimeVaultReader.java:61)
        ... 15 more

If I add the jar as a to org.picketbox it works.