title: How to modify Http headers before executing request in spring boot mvc
body: <p>I have  multiple rest endpoints. userId (http header) is common in all endpoints. I want to apply a logic, let say set its default value if not provided or trim it if is provided in request before request enters the method (for eg: heartbeat). How can we achieve this in spring boot rest mvc.</p>
  
  <pre><code>@RestController
  public class MyResource {
  
  
  
          @RequestMapping(value = "/heartbeat", method= RequestMethod.GET)
          public String heartbeat (@RequestHeader (value="userId", required=false) String userId) 
          {
             ...
          }
      }
  </code></pre>