code: public function getIndicesOfSerializableParameters()
      {
          $indices = [];
          for ($i = 0; $i < count($this->parameterTypes); $i++) {
              if (0 !== strpos($this->parameterTypes[$i], '@')) {
                  $indices[] = $i;
              }
          }
  
          return $indices;
      }
docs: {@inheritdoc}