done

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

+import org.springframework.web.bind.annotation.RequestMapping
+import org.springframework.web.bind.annotation.RestController
+
+@RestController
+class ThisWillActuallyRun {
+
+    @RequestMapping("/")
+    String home() {
+        return "Hello World!"
+    }
+
+}