/**
  * Get user permission
  *
  * @param Group $group
  * @return GroupUserPermission|NULL
  */
 public function getUserPermission(Group $group)
 {
     static $permissions = array();
     if (array_key_exists($group->getRole(), $permissions)) {
         return $permissions[$group->getRole()];
     }
     if (($user = $this->tokenStorage->getToken()->getUser()) instanceof User) {
         foreach ($user->getGroupPermissions() as $permission) {
             if ($permission->getGroup()->isEqualTo($group)) {
                 return $permissions[$group->getRole()] = $permission;
             }
         }
     }
     return null;
 }