FOS\UserBundle\Model\UserInterface::setPassword PHP Method

    function setPassword($password);

 /**
  * Attach OAuth sign-in provider account to existing user
  *
  * @param FOSUserInterface      $user
  * @param UserResponseInterface $response
  *
  * @return FOSUserInterface
  */
 protected function updateUserByOAuthUserResponse(FOSUserInterface $user, UserResponseInterface $response)
 {
     $providerName = $response->getResourceOwner()->getName();
     $providerNameSetter = 'set' . ucfirst($providerName) . 'Id';
     $user->{$providerNameSetter}($response->getUsername());
     if (!$user->getPassword()) {
         // generate unique token
         $secret = md5(uniqid(rand(), true));
         $user->setPassword($secret);
     }
     return $user;
 }