title: Issues with service instances marked as final in spring-boot controller?
body: <p>What are the issues with marking a spring-service instance as final in a spring-controller (sample code below)?</p>
  
  <p>If everything in spring is a singleton by default is this just overkill? Also in case it's relevant the <strong>@autowired</strong> annotation is not being used.</p>
  
  <pre><code>@RestController
  @RequestMapping("/controller")
  public class MyController {
      private final MyService myService;
  
      ....
  }
  </code></pre>