done

initial/src/main/java/hello/App.java

@@ -0,0 +1,11 @@
+package hello;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+public class App {
+    public static void main(String[] args) {
+        SpringApplication.run(App.class, args);
+    }
+}

initial/src/main/java/hello/Greeting.java

@@ -0,0 +1,19 @@
+package hello;
+
+public class Greeting {
+    private final long id;
+    private final String content;
+
+    public Greeting(long id, String content) {
+        this.id = id;
+        this.content = content;
+    }
+
+    public long getId() {
+        return id;
+    }
+
+    public String getContent() {
+        return content;
+    }
+}

initial/src/main/java/hello/GreetingController.java

@@ -0,0 +1,19 @@
+package hello;
+
+import java.util.concurrent.atomic.AtomicLong;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RequestParam;
+import org.springframework.web.bind.annotation.RestController;
+
+@RestController
+public class GreetingController {
+    private static final String template = "Hello, %s!";
+    private final AtomicLong counter = new AtomicLong();
+
+    @RequestMapping("/greeting")
+    public Greeting greeting(@RequestParam(value = "name", defaultValue = "World") String name) {
+        return new Greeting(counter.incrementAndGet(),
+                String.format(template, name));
+    }
+}
+