How to show (AddProblemDetails) multiple validation error against single property using Fluent Validation & MediatR Pipeline Behaviour about middleware HOT 3 OPEN

 public class ValidationException : Exception
{
    public IDictionary<string, string[]> Errors { get; } 
    public ValidationException(string message, int? code = null) : base(message, code: code)
    {
        Errors = new Dictionary<string, string[]>();
    }

    public ValidationException(IEnumerable<ValidationFailure> failures):this("One or more validation failures have occurred.")
    {
        Errors = failures
            .GroupBy(e => e.PropertyName, e => e.ErrorMessage)
            .ToDictionary(failureGroup => failureGroup.Key, failureGroup => failureGroup.ToArray());
    }
}

 public sealed class ValidationBehavior<TRequest, TResponse> : IPipelineBehavior<TRequest, TResponse>
   where TRequest : class, IRequest<TResponse>
  {
      private readonly IEnumerable<IValidator<TRequest>> _validators;
      private readonly IServiceProvider _serviceProvider;

      public ValidationBehavior(IServiceProvider serviceProvider, IEnumerable<IValidator<TRequest>> validators)
      {
          _serviceProvider = serviceProvider;
          _validators = validators;
      }
      public async Task<TResponse> Handle(TRequest request, CancellationToken cancellationToken, RequestHandlerDelegate<TResponse> next)
      {
          if (_validators.Any())
          {
              var context = new ValidationContext<TRequest>(request);

              var validationResults = await Task.WhenAll(
                  _validators.Select(v =>
                      v.ValidateAsync(context, cancellationToken)));

              var failures = validationResults
                  .Where(r => r.Errors.Any())
                  .SelectMany(r => r.Errors)
                  .ToList();

              if (failures.Any())
                  throw new ValidationException(failures);
          }
          return await next();
      }
  }

     public static IServiceCollection AddCustomProblemDetails(this IServiceCollection services)
      {
          services.AddProblemDetails(x =>
          {
               x.IncludeExceptionDetails = (ctx, _) =>
              {
                  // Fetch services from HttpContext.RequestServices
                  var env = ctx.RequestServices.GetRequiredService<IHostEnvironment>();
                  return env.IsDevelopment() || env.IsStaging();
              };
           
            // Exception will produce and returns from  FluentValidation RequestValidationBehavior
            x.Map<ValidationException>(ex => new ProblemDetailsWithCode
            {
                Title = "input validation rules broken",
                Status = (int)ex.StatusCode,
                Detail = ex.Message,
                Type = "https://somedomain/input-validation-rules-error", 
            });
          
        });
        return services;
    }