Didn't you notice this in you server.log ?

ERROR [org.jboss.nukes.system.JDBCPersistenceManager] Cannot sync attribute
org.jboss.nukes.utils.ConversionException: A property editor has not been found for type java.util.Map
 at org.jboss.nukes.utils.Tools.findEditor(Tools.java:777)
 at org.jboss.nukes.utils.Tools.fromObject(Tools.java:831)

That's because the Map defaultValues is exposed in the jmx bean.
So just make the setDefaultValues method private in JmxModule.java :

private void setDefaultValues(Map defaultValues)
 {
 this.defaultValues = defaultValues;
 }