Putting the dummy url to the last of url list like:
<connection-url>jdbc:postgresql://node1:5432/jboss|jdbc:postgresql://node2:5432/jboss|jdbc:postgresql://node3:5432/jboss|jdbc:postgresql://dummyhost:5432/jboss</connection-url>
See https://bugzilla.redhat.com/show_bug.cgi?id=1120892