anchor.diff:  
               Data0 = lists:map(fun({{Property, {maybe, _Type}, _Length, _Text}, ""}) ->
                                         %% ok to skip
  -                                      {Property, null};
  +                                      {Property, null_null_null};
                                    ({{Property, {maybe, Type}, Length, _Text}, Col}) ->
                                         to_json_object(Property, Type, Length, Col);
   
  
positive.code:             {Tokens, _}  = lists:split(ShortLen, Tokens0),
  
              Data0 = lists:map(fun({{Property, _Type}, []}) ->
                                        {klib:maybe_binary(Property), null};
                                   ({{Property, Type}, Tok}) ->
                                        {klib:maybe_binary(Property),
                                         to_json_object(Type, Tok, Depth+1)}
                                end,
                                lists:zip(TypeDef, Tokens)),
              Data = lists:filter(fun({_,null}) -> false;
                                     (_) -> true end, Data0),
              {Data} %% jsone requres {_} as JSON object
      end.
  
negative.code:                                       treehugger:hug(Tree, warning,
                                                       "empty property '~s' which isn't optional in ~s~n",
                                                      [Property, File]),
                                        {Property, null_null_null};
                                        
                                   ({{Property, Type, Length, _Text}, Col}) ->
                                        %% ?debugVal({Property, Type}),
                                        to_json_object(Property, Type, Length, Col)
                        end,
                        lists:zip(MsgDef, Tokens)),
              Data = lists:filter(fun({_,null_null_null}) -> false;
                                     (_) -> true end, Data0),
  
              case get_observation_value(Data) of
  