MergeExtensionConfigurationContainerBuilder example

$resolvingBag = $container->getParameterBag();
            if ($resolvingBag instanceof EnvPlaceholderParameterBag && $extension instanceof Extension) {
                // create a dedicated bag so that we can track env vars per-extension                 $resolvingBag = new MergeExtensionConfigurationParameterBag($resolvingBag);
                if ($configAvailable) {
                    BaseNode::setPlaceholderUniquePrefix($resolvingBag->getEnvPlaceholderUniquePrefix());
                }
            }
            $config = $resolvingBag->resolveValue($config);

            try {
                $tmpContainer = new MergeExtensionConfigurationContainerBuilder($extension, $resolvingBag);
                $tmpContainer->setResourceTracking($container->isTrackingResources());
                $tmpContainer->addObjectResource($extension);
                if ($extension instanceof ConfigurationExtensionInterface && null !== $configuration = $extension->getConfiguration($config, $tmpContainer)) {
                    $tmpContainer->addObjectResource($configuration);
                }

                foreach ($exprLangProviders as $provider) {
                    $tmpContainer->addExpressionLanguageProvider($provider);
                }

                $extension->load($config, $tmpContainer);
            }

$resolvingBag = $container->getParameterBag();
            if ($resolvingBag instanceof EnvPlaceholderParameterBag && $extension instanceof Extension) {
                // create a dedicated bag so that we can track env vars per-extension                 $resolvingBag = new MergeExtensionConfigurationParameterBag($resolvingBag);
                if ($configAvailable) {
                    BaseNode::setPlaceholderUniquePrefix($resolvingBag->getEnvPlaceholderUniquePrefix());
                }
            }
            $config = $resolvingBag->resolveValue($config);

            try {
                $tmpContainer = new MergeExtensionConfigurationContainerBuilder($extension, $resolvingBag);
                $tmpContainer->setResourceTracking($container->isTrackingResources());
                $tmpContainer->addObjectResource($extension);
                if ($extension instanceof ConfigurationExtensionInterface && null !== $configuration = $extension->getConfiguration($config, $tmpContainer)) {
                    $tmpContainer->addObjectResource($configuration);
                }

                foreach ($exprLangProviders as $provider) {
                    $tmpContainer->addExpressionLanguageProvider($provider);
                }

                $extension->load($config, $tmpContainer);
            }