private static string GetMessage(ModelStateResponse ms)
 {
     if (ms.ModelState == null)
     {
         return(ms.Message);
     }
     return($"{string.Join("\n", ms.ModelState.SelectMany(kv => kv.Value)).Replace(". ", "\n")}");
 }
 public BadRequestException(ModelStateResponse modelState)
     : base(GetMessage(modelState))
 {
 }