code: public function getAddonsForPlan(array $plans, string $addonType = null): array
      {
          $addonApi = new Addon($this->token, $this->organizationId, $this->cache, $this->ttl);
  
          foreach ($plans as &$plan) {
              $addons = [];
  
              foreach ($plan['addons'] as $planAddon) {
                  $addon = $addonApi->getAddon($planAddon['addon_code']);
  
                  if (null !== $addonType) {
                      if (($addon['type'] == $addonType) && (in_array($addonType, self::$addonTypes))) {
                          $addons[] = $addon;
                      }
                  } else {
                      $addons[] = $addon;
                  }
              }
  
              $plan['addons'] = $addons;
          }
  
          return $plans;
      }
docs: get reccurent addons for given plan.
  
  @param array  $plans
  @param string|null $addonType
  
  @return array