Adapt to API change in Spring Framework

See spring-projects/spring-framework#29005

Author: snicoll

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/web/server/ChildManagementContextInitializer.java

@@ -22,7 +22,6 @@
 
 import org.springframework.aot.generate.GeneratedMethod;
 import org.springframework.aot.generate.GenerationContext;
-import org.springframework.aot.generate.MethodReference;
 import org.springframework.beans.factory.BeanFactory;
 import org.springframework.beans.factory.aot.BeanRegistrationAotContribution;
 import org.springframework.beans.factory.aot.BeanRegistrationAotProcessor;
@@ -172,8 +171,7 @@ public void applyTo(GenerationContext generationContext, BeanRegistrationCode be
 							.returns(ChildManagementContextInitializer.class)
 							.addStatement("return instance.withApplicationContextInitializer(new $L())",
 									generatedInitializerClassName));
-			beanRegistrationCode.addInstancePostProcessor(
-					MethodReference.ofStatic(beanRegistrationCode.getClassName(), postProcessorMethod.getName()));
+			beanRegistrationCode.addInstancePostProcessor(postProcessorMethod.toMethodReference());
 		}
 
 	}