anchor.diff:  
   occi_request returns [String request]
     : occi_header
  -    {$request = "[" + $occi_header.header + "]";}
  +    {$request = "[{" + $occi_header.header + "}]";}
     | multi_val1 = occi_header
  -    {$request = "[" + $multi_val1.header;}
  +    {$request = "[{" + $multi_val1.header;}
       (
         multi_val2 = occi_header
         {$request += ", " + $multi_val2.header;}
       )+
  -    {$request += "]";}
  +    {$request += "}]";}
   ;
   occi_header returns [String header]
     : category_header {$header = $category_header.category;}
  
positive.code: */
  location_header returns [String locations_val]
    : LOCATION_HEADER location_paths
      {$locations_val = "{\"location\":" + $location_paths.locations_vals + "}";}
  ;
  location_paths returns [String locations_vals]
    : single_loc = location_path
  
negative.code: */
  attribute_header returns [String attribute_header]
    : ATTR_HEADER attribute_attrs
      {$attribute_header = "\"attributes\":{"+$attribute_attrs.attribute_attrs+"}";}
  ;
  attribute_attrs returns [String attribute_attrs]
    : attribute_attr
  