Symfony\Component\DependencyInjection\ContainerBuilder::getExtensionConfig PHP Method

    public function getExtensionConfig($name)
    {
        if (!isset($this->extensionConfigs[$name])) {
            $this->extensionConfigs[$name] = array();
        }

        return $this->extensionConfigs[$name];
    }

 /**
  * {@inheritdoc}
  */
 public function prepend(ContainerBuilder $container)
 {
     $config = current($container->getExtensionConfig('oauth2_server'));
     Assertion::keyExists($config, 'token_endpoint', 'The "TokenEndpointPlugin" must be enabled to use the "JWTBearerPlugin".');
     $bundle_config = current($container->getExtensionConfig('oauth2_server'))[$this->name()];
     $this->updateJoseBundleConfigurationForVerifier($container, 'jwt_bearer_grant_type', $bundle_config);
     $this->updateJoseBundleConfigurationForDecrypter($container, 'jwt_bearer_grant_type', $bundle_config);
     $this->updateJoseBundleConfigurationForChecker($container, 'jwt_bearer_grant_type', $bundle_config);
     $this->updateJoseBundleConfigurationForJWTLoader($container, 'jwt_bearer_grant_type', $bundle_config);
 }