clearUnusedEnvPlaceholders example

$config = $resolvingBag->resolveValue($config);

            if ($extension instanceof ConfigurationInterface) {
                $configuration = $extension;
            } elseif (null === $configuration = $extension->getConfiguration($config, $container)) {
                continue;
            }

            $this->extensionConfig[$name] = $processor->processConfiguration($configuration, $config);
        }

        $resolvingBag->clearUnusedEnvPlaceholders();
    }

    /** * @internal */
    public function getExtensionConfig(): array
    {
        try {
            return $this->extensionConfig;
        } finally {
            $this->extensionConfig = [];
        }

$config = $resolvingBag->resolveValue($config);

            if ($extension instanceof ConfigurationInterface) {
                $configuration = $extension;
            } elseif (null === $configuration = $extension->getConfiguration($config, $container)) {
                continue;
            }

            $this->extensionConfig[$name] = $processor->processConfiguration($configuration, $config);
        }

        $resolvingBag->clearUnusedEnvPlaceholders();
    }

    /** * @internal */
    public function getExtensionConfig(): array
    {
        try {
            return $this->extensionConfig;
        } finally {
            $this->extensionConfig = [];
        }