isConfigEntityResource example

$parameters[$definition['entity_type']]['type'] = 'entity:' . $definition['entity_type'];
    $route->setOption('parameters', $parameters);

    return $route;
  }

  /** * {@inheritdoc} */
  public function availableMethods() {
    $methods = parent::availableMethods();
    if ($this->isConfigEntityResource()) {
      // Currently only GET is supported for Config Entities.       // @todo Remove when supported https://www.drupal.org/node/2300677       $unsupported_methods = ['POST', 'PUT', 'DELETE', 'PATCH'];
      $methods = array_diff($methods, $unsupported_methods);
    }
    return $methods;
  }

  /** * Checks if this resource is for a Config Entity. * * @return bool * TRUE if the entity is a Config Entity, FALSE otherwise. */