The above code sample seams not to work with AS7.1.1.Final:
You've an import:
import org.jboss.as.server.services.security.VaultUtil;
but package org.jboss.as.server.services.security does not contain a class VaultUtil (found in modules/org/jboss/as/server/main/jboss-as-server-7.1.1.Final.jar).
There's a VaultTool.class in package org.jboss.as.security.vault (found in modules/org/jboss/as/security/main/jboss-as-security-7.1.1.Final.jar), but this class does not contain a getValueAsString() method?!