public async Task HandleAsync(MessageY message)
        {
            await Task.Yield();

            Assert.IsNotNull(message);
            Assert.AreEqual(34, message.I);
        }
        public void Handle(MessageY message)
        {
            Assert.IsNotNull(message);
            Assert.AreEqual(34, message.I);

            if (message.Fail)
            {
                throw new Exception("Fail");
            }
        }