Remove FromBodyOnProperty_RequiredOnValueTypeSubProperty_AddsModelStateError

- this integration test depends on the old `[Required]` special case
- aspnet#2388 explicitly removes that bahaviour so the test goes with it

Author: dougbu

test/Microsoft.AspNet.Mvc.IntegrationTests/BodyValidationIntegrationTests.cs

@@ -220,67 +220,5 @@ public async Task FromBodyOnTopLevelProperty_RequiredOnSubProperty_AddsModelStat
             var error = Assert.Single(modelState[street].Errors);
             Assert.Equal("The Street field is required.", error.ErrorMessage);
         }
-
-        private class Person3
-        {
-            [FromBody]
-            public Address3 Address { get; set; }
-        }
-
-        private class Address3
-        {
-            public string Street { get; set; }
-
-            [Required]
-            public int Zip { get; set; }
-        }
-
-        [Theory]
-        [InlineData("{ \"Street\" : \"someStreet\" }")]
-        [InlineData("{}")]
-        public async Task FromBodyOnProperty_RequiredOnValueTypeSubProperty_AddsModelStateError(string inputText)
-        {
-            // Arrange
-            var argumentBinder = ModelBindingTestHelper.GetArgumentBinder();
-            var parameter = new ParameterDescriptor()
-            {
-                BindingInfo = new BindingInfo()
-                {
-                    BinderModelName = "CustomParameter",
-                },
-                ParameterType = typeof(Person3)
-            };
-
-            var operationContext = ModelBindingTestHelper.GetOperationBindingContext(
-                request =>
-                {
-                    request.Body = new MemoryStream(Encoding.UTF8.GetBytes(inputText));
-                    request.ContentType = "application/json";
-                });
-            var httpContext = operationContext.HttpContext;
-            var actionContext = httpContext.RequestServices.GetRequiredService<IScopedInstance<ActionContext>>().Value;
-            var modelState = actionContext.ModelState;
-
-            // Act
-            var modelBindingResult = await argumentBinder.BindModelAsync(parameter, modelState, operationContext);
-
-            // Assert
-            Assert.NotNull(modelBindingResult);
-            Assert.True(modelBindingResult.IsModelSet);
-            var boundPerson = Assert.IsType<Person3>(modelBindingResult.Model);
-            Assert.NotNull(boundPerson);
-            Assert.False(modelState.IsValid);
-            var street = Assert.Single(modelState.Keys, k => k == "CustomParameter.Address.Street");
-            Assert.Equal(ModelValidationState.Valid, modelState[street].ValidationState);
-
-            // The error with an empty key is a bug(#2416) in our implementation which does not append the prefix and
-            // use that along with the path. The expected key here would be Address.
-            var zip = Assert.Single(modelState.Keys, k => k == "CustomParameter.Address.Zip");
-            Assert.Equal(ModelValidationState.Valid, modelState[zip].ValidationState);
-            var error = Assert.Single(modelState[""].Errors);
-            Assert.StartsWith(
-                "Required property 'Zip' not found in JSON. Path ''",
-                error.Exception.Message);
-        }
     }
 }