code: public List<Property> asPropertyList() throws IllegalArgumentException {
          if(ModelValue.UNDEFINED == value)
              return Collections.EMPTY_LIST;
          else
              return value.asPropertyList();
      }
docs: Get the value of this node as a property list.  Object values will return a list of properties representing
  each key-value pair in the object.  List values will return all the values of the list, failing if any of the
  values are not convertible to a property value.
  
  @return the property list value
  @throws IllegalArgumentException if no conversion is possible