code: public List<String> getExtraFieldNames()
      {
          List<String> result = new ArrayList<String>();
  
          for (Method method : getExtraFieldMethods())
          {
              ExtraField extraField = method.getAnnotation( ExtraField.class );
              result.add( extraField.value() );
          }
  
          return result;
      }
docs: This method returns a list of the field names for @ExtraField methods in this object.
  
  @return A list of string field names