Fix issue with resolving Errors controller argument

The ErrorsMethodArgumentResolver expects the preceding @ModelAttribute
in the controller method signature to be the last one added in the
model -- an assumption that can break if a model attribute is added
earlier (e.g. through a @ModelAttribute method) and more attributes
are added as well. This fix ensures when an @ModelAttribute is resolved
as a controller method argument it has the highest index in the model.

Issue: SPR-9378
Backport Issue: SPR-9687

org.springframework.web/src/main/java/org/springframework/web/method/annotation/ModelAttributeMethodProcessor.java

@@ -17,10 +17,10 @@
 package org.springframework.web.method.annotation;
 
 import java.lang.annotation.Annotation;
+import java.util.Map;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
-
 import org.springframework.beans.BeanUtils;
 import org.springframework.core.MethodParameter;
 import org.springframework.core.annotation.AnnotationUtils;
@@ -31,7 +31,6 @@ import org.springframework.web.bind.annotation.ModelAttribute;
 import org.springframework.web.bind.support.WebDataBinderFactory;
 import org.springframework.web.bind.support.WebRequestDataBinder;
 import org.springframework.web.context.request.NativeWebRequest;
-import org.springframework.web.method.annotation.ModelFactory;
 import org.springframework.web.method.support.HandlerMethodArgumentResolver;
 import org.springframework.web.method.support.HandlerMethodReturnValueHandler;
 import org.springframework.web.method.support.ModelAndViewContainer;
@@ -113,7 +112,12 @@ public class ModelAttributeMethodProcessor implements HandlerMethodArgumentResol
 			}
 		}
 
-		mavContainer.addAllAttributes(binder.getBindingResult().getModel());
+		// Add resolved attribute and BindingResult at the end of the model
+
+		Map<String, Object> bindingResultModel = binder.getBindingResult().getModel();
+		mavContainer.removeAttributes(bindingResultModel);
+		mavContainer.addAllAttributes(bindingResultModel);
+
 		return binder.getTarget();
 	}
 

org.springframework.web/src/main/java/org/springframework/web/method/support/ModelAndViewContainer.java

@@ -223,6 +223,18 @@ public class ModelAndViewContainer {
 		return this;
 	}
 
+	/**
+	 * Remove the given attributes from the model.
+	 */
+	public ModelAndViewContainer removeAttributes(Map<String, ?> attributes) {
+		if (attributes != null) {
+			for (String key : attributes.keySet()) {
+				getModel().remove(key);
+			}
+		}
+		return this;
+	}
+
 	/**
 	 * Whether the underlying model contains the given attribute name.
 	 * @see ModelMap#containsAttribute(String)