code: private function addSource(array $arguments = array())
      {
          $this->builder->addSource(
              array_key_exists('cache', $this->source) ? $this->createCacheAdapter() : new HttpApiAdapter(),
              new Request(array(
                  'source' => $this->source,
                  'arguments' => $arguments,
                  'service' => $this->getGroup()->getService()->getName(),
                  'group' => $this->getGroup()->getName(),
                  'action' => $this->getName(),
              )));
      }
docs: Adds source adapter.
  
  @param array $arguments