public function add(User $user)
 {
     if (null !== $this->find($user->getId())) {
         throw new \InvalidArgumentException('User already exists');
     }
     $this->users[] = $user;
 }
 public static function fromUser(User $user)
 {
     return new static(['id' => $user->getId(), 'email' => $user->getEmail(), 'name' => $user->getName()]);
 }