Prevent warning due to BPP dependency

`MethodValidationPostProcessor` requires a `Validator` so we need to flag
it as an infrastructure bean to prevent an additional log that indicates
it won't be post-processed.

We obviously don't want to post-process the `Validator` here so adding the
additional meta-data is a good idea anyway.

Closes gh-8422

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/validation/ValidationAutoConfiguration.java

@@ -19,12 +19,15 @@ package org.springframework.boot.autoconfigure.validation;
 import javax.validation.Validator;
 import javax.validation.executable.ExecutableValidator;
 
+import org.springframework.beans.factory.config.BeanDefinition;
 import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnResource;
 import org.springframework.boot.validation.MessageInterpolatorFactory;
 import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.context.annotation.Role;
 import org.springframework.validation.beanvalidation.LocalValidatorFactoryBean;
 import org.springframework.validation.beanvalidation.MethodValidationPostProcessor;
 
@@ -35,13 +38,15 @@ import org.springframework.validation.beanvalidation.MethodValidationPostProcess
  * @author Stephane Nicoll
  * @since 1.5.0
  */
+@Configuration
 @ConditionalOnClass(ExecutableValidator.class)
 @ConditionalOnResource(resources = "classpath:META-INF/services/javax.validation.spi.ValidationProvider")
 public class ValidationAutoConfiguration {
 
 	@Bean
+	@Role(BeanDefinition.ROLE_INFRASTRUCTURE)
 	@ConditionalOnMissingBean
-	public Validator validator() {
+	public static Validator validator() {
 		LocalValidatorFactoryBean factoryBean = new LocalValidatorFactoryBean();
 		MessageInterpolatorFactory interpolatorFactory = new MessageInterpolatorFactory();
 		factoryBean.setMessageInterpolator(interpolatorFactory.getObject());
@@ -50,7 +55,7 @@ public class ValidationAutoConfiguration {
 
 	@Bean
 	@ConditionalOnMissingBean
-	public MethodValidationPostProcessor methodValidationPostProcessor(
+	public static MethodValidationPostProcessor methodValidationPostProcessor(
 			Validator validator) {
 		MethodValidationPostProcessor processor = new MethodValidationPostProcessor();
 		processor.setProxyTargetClass(true);