Add AopAutoConfiguration (also starter and sample)

A side effect is that spring-boot-starter-data-jpa needs
to include an aspectjweaver depdendency. Hope that doesn't
hurt anything else.

[Fixes #56780004]

spring-boot-samples/spring-boot-sample-aop/src/main/java/org/springframework/boot/sample/aop/SampleAopApplication.java

@@ -0,0 +1,45 @@
+/*
+ * Copyright 2013 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.sample.aop;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.CommandLineRunner;
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
+import org.springframework.boot.sample.aop.service.HelloWorldService;
+import org.springframework.context.annotation.ComponentScan;
+import org.springframework.context.annotation.Configuration;
+
+@Configuration
+@EnableAutoConfiguration
+@ComponentScan
+public class SampleAopApplication implements CommandLineRunner {
+
+	// Simple example shows how an application can spy on itself with AOP
+
+	@Autowired
+	private HelloWorldService helloWorldService;
+
+	@Override
+	public void run(String... args) {
+		System.out.println(this.helloWorldService.getHelloMessage());
+	}
+
+	public static void main(String[] args) throws Exception {
+		SpringApplication.run(SampleAopApplication.class, args);
+	}
+}

spring-boot-samples/spring-boot-sample-aop/src/main/java/org/springframework/boot/sample/aop/monitor/ServiceMonitor.java

@@ -0,0 +1,17 @@
+package org.springframework.boot.sample.aop.monitor;
+
+import org.aspectj.lang.JoinPoint;
+import org.aspectj.lang.annotation.AfterReturning;
+import org.aspectj.lang.annotation.Aspect;
+import org.springframework.stereotype.Component;
+
+@Aspect
+@Component
+public class ServiceMonitor {
+	
+	@AfterReturning("execution(* *..*Service.*(..))")
+	public void logServiceAccess(JoinPoint joinPoint) {
+		System.out.println("Completed: " + joinPoint);
+	}
+
+}

spring-boot-samples/spring-boot-sample-aop/src/main/java/org/springframework/boot/sample/aop/service/HelloWorldService.java

@@ -0,0 +1,32 @@
+/*
+ * Copyright 2013 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.sample.aop.service;
+
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.stereotype.Component;
+
+@Component
+public class HelloWorldService {
+
+	@Value("${name:World}")
+	private String name;
+
+	public String getHelloMessage() {
+		return "Hello " + this.name;
+	}
+
+}