title: Symfony 2 UserInterface::equals($user): Comparing for re-authentication
body: <p>From the UserInterface class</p>
  
  <pre><code>interface UserInterface {
      /**
       * The equality comparison should neither be done by referential equality
       * nor by comparing identities (i.e. getId() === getId()).
       *
       * However, you do not need to compare every attribute, but only those that
       * are relevant for assessing whether re-authentication is required.
       *
       * @param UserInterface $user
       * @return Boolean
       */
      function equals(UserInterface $user);
  }
  </code></pre>
  
  <p>How should I implement this ("<em>those relevant for assessing whether re-authentication is required</em>")? So does this mean its after Symfony 2 reauthenticated (username/password) the user? Or is this function user to reauthenticated. Do I check <code>id, username, password, salt</code> maybe? Doesn't Symfony reauthenticate the user by password check, which should be enough? </p>