Imported Upstream version 4.0.0~alpha1

Former-commit-id: 806294f5ded97629b74c85c09952f2a74fe182d9

external/referencesource/System.Web/ModelBinding/MutableObjectModelBinderProvider.cs

@@ -0,0 +1,22 @@
+namespace System.Web.ModelBinding {
+
+    public sealed class MutableObjectModelBinderProvider : ModelBinderProvider {
+
+        public override IModelBinder GetBinder(ModelBindingExecutionContext modelBindingExecutionContext, ModelBindingContext bindingContext) {
+            ModelBinderUtil.ValidateBindingContext(bindingContext);
+
+            if (!bindingContext.UnvalidatedValueProvider.ContainsPrefix(bindingContext.ModelName)) {
+                // no values to bind
+                return null;
+            }
+
+            if (bindingContext.ModelType == typeof(ComplexModel)) {
+                // forbidden type - will cause a stack overflow if we try binding this type
+                return null;
+            }
+
+            return new MutableObjectModelBinder();
+        }
+
+    }
+}