async function init() {
  const users = await db.User.findAll();
  const plainUsers = users.map((user) => {
    const plainUser = user.get({ plain: true });
    this.stateManager.setState('user', plainUser.selector, plainUser);
    this.stateManager.setState('userById', plainUser.id, plainUser);
    return plainUser;
  });
  return plainUsers;
}
@description Load all users from the database.
@returns {Promise} Resolve when success.
@example
user.init();