fix param validation

spring-mvc-xml/src/main/java/com/baeldung/spring/ClientWebConfigJava.java

@@ -5,8 +5,10 @@ import java.util.ResourceBundle;
 
 import org.springframework.context.MessageSource;
 import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.ComponentScan;
 import org.springframework.context.support.MessageSourceResourceBundle;
 import org.springframework.context.support.ResourceBundleMessageSource;
+import org.springframework.validation.beanvalidation.MethodValidationPostProcessor;
 import org.springframework.web.servlet.ViewResolver;
 import org.springframework.web.servlet.config.annotation.ViewControllerRegistry;
 import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
@@ -15,6 +17,7 @@ import org.springframework.web.servlet.view.JstlView;
 
 //@EnableWebMvc
 //@Configuration
+@ComponentScan("com.baeldung.spring")
 public class ClientWebConfigJava implements WebMvcConfigurer {
 
     public ClientWebConfigJava() {
@@ -51,4 +54,9 @@ public class ClientWebConfigJava implements WebMvcConfigurer {
 
         return bean;
     }
+    
+    @Bean
+    public MethodValidationPostProcessor methodValidationPostProcessor() {
+        return new MethodValidationPostProcessor();
+    }
 }