$roles = [new \Symfony\Component\Security\Core\Role\Role('name')];
$user = new \Symfony\Component\Security\Core\User\User('name', 'password', $roles);
$token = new \Symfony\Component\Security\Core\Authentication\Token\UsernamePasswordToken($user, 'password', 'providerKey', $user->getRoles());

$serialized = serialize($token);
$unserialized = unserialize($token);

var_dump($serialized, $token->getRoles(), $unserialized->getRoles());

/*
Output:
string(859) "C:74:"Symfony\Component\Security\Core\Authentication\Token\UsernamePasswordToken":771:{a:3:{i:0;s:8:"password";i:1;s:11:"providerKey";i:2;s:710:"a:4:{i:0;O:41:"Symfony\Component\Security\Core\User\User":7:{s:51:"\000Symfony\Component\Security\Core\User\User\000username";s:4:"name";s:51:"\000Symfony\Component\Security\Core\User\User\000password";s:8:"password";s:50:"\000Symfony\Component\Security\Core\User\User\000enabled";b:1;s:60:"\000Symfony\Component\Security\Core\User\User\000accountNonExpired";b:1;s:64:"\000Symfony\Component\Security\Core\User\User\000credentialsNonExpired";b:1;s:59:"\000Symfony\Component\Security\Core\User\User\000accountNonLocked";b:1;s:48:"\000Symfony\Component\Security\Core\User\User\000roles";a:1:{i:0;O:41:"Symfony\Component\Security\Core\Role\Role":1:{s:47:"\000Symfony\Component\Security\Core\Role\Role\000role";s:4:"name";}}}i:1;b:1;i:2;a:1:{i:0;r:11;}i:3;a:0:{}}";}}"
array(1) {
  [0] =>
  class Symfony\Component\Security\Core\Role\Role#947 (1) {
    private $role =>
    string(4) "name"
  }
}
array(1) {
  [0] =>
  bool(true)
}
*/