services parameters 是如何表现的

  render_placeholder_generator:
    class: Drupal\Core\Render\PlaceholderGenerator
    arguments: ['%renderer.config%']

===============
    $this->rendererConfig = $renderer_config;
//     kint($this->rendererConfig);
//     //$args array(1)
//     →array(2)
//     →'required_cache_contexts' => array(3)
//     string(28) "languages:language_interface"
//       string(5) "theme"
//         string(16) "user.permissions"
//           →'auto_placeholder_conditions' => array(3)
//           'max-age' => integer0
//           →'contexts' => array(2)
//           string(7) "session"
//             string(4) "user"
//             'tags' => array(0)