Avoid using invalid content type for ValidationProblemDetails (#36618)

Co-authored-by: Safia Abdalla <safia@microsoft.com>

Author: github-actions[bot]

src/Http/Routing/src/Builder/OpenApiDelegateEndpointConventionBuilderExtensions.cs

@@ -109,15 +109,15 @@ public static DelegateEndpointConventionBuilder ProducesProblem(this DelegateEnd
         /// </summary>
         /// <param name="builder">The <see cref="DelegateEndpointConventionBuilder"/>.</param>
         /// <param name="statusCode">The response status code. Defaults to StatusCodes.Status400BadRequest.</param>
-        /// <param name="contentType">The response content type. Defaults to "application/validationproblem+json".</param>
+        /// <param name="contentType">The response content type. Defaults to "application/problem+json".</param>
         /// <returns>A <see cref="DelegateEndpointConventionBuilder"/> that can be used to further customize the endpoint.</returns>
         public static DelegateEndpointConventionBuilder ProducesValidationProblem(this DelegateEndpointConventionBuilder builder,
             int statusCode = StatusCodes.Status400BadRequest,
             string? contentType = null)
         {
             if (string.IsNullOrEmpty(contentType))
             {
-                contentType = "application/validationproblem+json";
+                contentType = "application/problem+json";
             }
 
             return Produces<HttpValidationProblemDetails>(builder, statusCode, contentType);

src/Mvc/Mvc.ApiExplorer/test/ApiResponseTypeProviderTest.cs

@@ -715,7 +715,7 @@ public void GetApiResponseTypes_HandlesActionWithMultipleContentTypesAndProduces
             // Arrange
             var actionDescriptor = GetControllerActionDescriptor(typeof(TestController), nameof(TestController.GetUser));
             actionDescriptor.FilterDescriptors.Add(new FilterDescriptor(new ProducesAttribute("text/xml") { Type = typeof(BaseModel) }, FilterScope.Action));
-            actionDescriptor.FilterDescriptors.Add(new FilterDescriptor(new ProducesResponseTypeAttribute(typeof(ValidationProblemDetails), 400, "application/validationproblem+json"), FilterScope.Action));
+            actionDescriptor.FilterDescriptors.Add(new FilterDescriptor(new ProducesResponseTypeAttribute(typeof(ValidationProblemDetails), 400, "application/problem+json"), FilterScope.Action));
             actionDescriptor.FilterDescriptors.Add(new FilterDescriptor(new ProducesResponseTypeAttribute(typeof(ProblemDetails), 404, "application/problem+json"), FilterScope.Action));
             actionDescriptor.FilterDescriptors.Add(new FilterDescriptor(new ProducesResponseTypeAttribute(409), FilterScope.Action));
 
@@ -738,7 +738,7 @@ public void GetApiResponseTypes_HandlesActionWithMultipleContentTypesAndProduces
                 {
                     Assert.Equal(typeof(ValidationProblemDetails), responseType.Type);
                     Assert.Equal(400, responseType.StatusCode);
-                    Assert.Equal(new[] { "application/validationproblem+json" }, GetSortedMediaTypes(responseType));
+                    Assert.Equal(new[] { "application/problem+json" }, GetSortedMediaTypes(responseType));
                 },
                 responseType =>
                 {

src/Mvc/Mvc.ApiExplorer/test/EndpointMetadataApiDescriptionProviderTest.cs

@@ -603,7 +603,7 @@ public void HandlesProducesWithProducesProblem()
                 {
                     Assert.Equal(typeof(HttpValidationProblemDetails), responseType.Type);
                     Assert.Equal(400, responseType.StatusCode);
-                    Assert.Equal(new[] { "application/validationproblem+json" }, GetSortedMediaTypes(responseType));
+                    Assert.Equal(new[] { "application/problem+json" }, GetSortedMediaTypes(responseType));
                 },
                 responseType =>
                 {