/**
  * get a contribution depending on user
  * If none yet, create one
  *
  * @param UserInterface $user Current user
  *
  * @return Contribution
  */
 private function getOrGenerateContribution(UserInterface $user = null)
 {
     if ($user) {
         $contribution = $this->getDoctrine()->getEntityManager()->getRepository('AFUP\\HaphpyBirthdayBundle\\Entity\\Contribution')->findOneBy(['authProvider' => $user->getAuthProvider(), 'identifier' => $user->getUsername()]);
         if ($contribution) {
             return $contribution;
         }
         $contribution = new Contribution();
         $contribution->setAuthProvider($user->getAuthProvider());
         $contribution->setIdentifier($user->getUsername());
         $contribution->setVisibleName($user->getVisibleName());
         return $contribution;
     }
     return new Contribution();
 }