anchor.diff:    SetTagChanged(false);
   end;
   
  -function TAbstractNullable.AsJson(const aFieldName: String; const aSkipIfNull, aAddComma: boolean): String;
  +function TAbstractNullable.AsJson(const aFieldName: String; const aSkipIfNull: boolean): String;
   begin
     if Self.IsNull and aSkipIfNull then
       Result := ''
     else
  -  begin
       Result := '"' + aFieldName + '":"' + Self.AsString + '"';
  -    if aAddComma then
  -      Result := Result + ',';
  -  end;
   end;
   
   end.
  
positive.code:   end;
  
  
  
  
  implementation
  
negative.code: 
      function CheckIfDifferentAndAssign(const aValue : Variant) : boolean; virtual; abstract;
      function AsString: String; virtual; abstract;
      function AsJson(const aFieldName : String; const aSkipIfNull : boolean): String; virtual;
  
      property IsNull: Boolean read GetIsNull write SetIsNull;
      property NotNull: Boolean read GetNotNull;
  