public function refreshContinent(Continent $continent)
    {

        $refreshedContinent = $this->findContinentBy(array('id' => $continent->getId()));
        if (null === $refreshedContinent) {
            throw new UsernameNotFoundException(sprintf('User with ID "%d" could not be reloaded.', $continent->getId()));
        }
        return $refreshedContinent;
    }