code: public function build()
      {
          $view = $change = array();
          foreach ($this->assigned as $resourceId => $spec) {
              /* This is needed to convert old permissions to the new spec format
               * introduced in 0.18
               * TODO: Remove this line some versions later.
               */
              // @codeCoverageIgnoreStart
              if (isset($spec['permission'])) {
                  $spec = array($spec['permission'] => $spec['users']);
                  $this->assigned[$resourceId] = $spec;
              }
              // @codeCoverageIgnoreEnd
  
              foreach ($spec as $perm => $userIds) {
                  if (self::PERMISSION_ALL == $perm || self::PERMISSION_CHANGE == $perm) {
                      $change = array_merge($change, $userIds);
                  }
                  $view = array_merge($view, $userIds);
              }
          }
          
          $this->change = array_unique($change);
          $this->view   = array_unique($view);
          return $this;
      }
docs: Builds the user id lists.
  
  This will make database queries faster and also the calls to {@link isGranted()} will be faster.
  
  @return self