title: Spring - validation of Integer attribute
body: <p>I have entity:</p>
  
  <pre><code>public class User{
     @NotNull
     private Integer age;
  } 
  </code></pre>
  
  <p>In Restcontroller: </p>
  
  <pre><code>@RestController
  public UserController {
   ..... 
  } 
  </code></pre>
  
  <p>I have BindingResult, but field age Spring doesn't validate. Can you tell me why? </p>
  
  <p>Thanks for your answers. </p>