FluentValidation integration with Mediatr sample

ValidationBehavior.cs

using MediatR;
using System.Reflection;
using System.Threading;
using System.Threading.Tasks;

namespace FrameworkExtensions.MediatR.Validation
{
    public class ValidationBehavior<TRequest, TResponse> : IPipelineBehavior<TRequest, TResponse>        
        where TResponse : IRequestResponse
    {
        private readonly PropertyInfo validationProperty;
        private readonly ValidatorCollection validators;

        public ValidationBehavior(ValidatorCollection validators)
        {
            this.validators = validators;
            
            var validateAttribute = typeof(TRequest).GetCustomAttribute<ValidateAttribute>();

            if (validateAttribute == null)
                return;

            validationProperty = typeof(TRequest).GetProperty(validateAttribute.PropertyName);
        }

        public async Task<TResponse> Handle(
            TRequest request,
            CancellationToken cancellationToken,
            RequestHandlerDelegate<TResponse> next)
        {
            if (validationProperty == null)
                return await next();

            var validator = validators.GetValidatorFor(validationProperty.PropertyType);

            var validationResult = await validator.ValidateAsync(validationProperty.GetValue(request, null), cancellationToken);

            if (!validationResult.IsValid)
                return RequestResponse.OfType<TResponse>(nameof(RequestResponse.NotOk), validationResult);

            var response = await next();
            response.ValidationResult = validationResult;

            return response;
        }        
    }
}