ModelMBeanInfoSupport.isValid() contains code that adds a default value
for various fields in the Descriptor for the ModelMBean itself. However,
the logic basically says:
   if (displayName missing)
      set default displayName
   else if (persistPolicy missing)
      set default persistPolicy
   else if (log missing)
      ...

Obviously the "else"s should not be there. Each one of these values that is missing should be added.