title: @RequestBody @Valid SomeDTO has field of enum type, custom error message
body: <p>I have the following <code>@RestController</code></p>
  
  <pre><code>@RequestMapping(...)
  public ResponseEntity(@RequestBody @Valid SomeDTO, BindingResult errors) {
  //do something with errors if validation error occur
  }
  
  public class SomeDTO {
     public SomeEnum someEnum;
  }
  </code></pre>
  
  <p>If the JSON request is <code>{ "someEnum": "valid value" }</code>, everything works fine. However, if the request is <code>{ "someEnum": "invalid value" }</code>, it only return error code 400.</p>
  
  <p>How can I trap this error so I can provide a custom error message, such as "someEnum must be of value A/B/C".</p>