src/DependencyInjection/Configuration.php
public function getConfigTreeBuilder()
    {
        $treeBuilder = new TreeBuilder('cache_adapter');

        if (method_exists($treeBuilder, 'getRootNode')) {
            $rootNode = $treeBuilder->getRootNode();
        } else {
            $rootNode = $treeBuilder->root('cache_adapter');
        }

        $rootNode->children()
            ->append($this->getClustersNode())
            ->end();

        return $treeBuilder;
    }
public function getConfigTreeBuilder()
    {
        $treeBuilder = new TreeBuilder('cache_adapter');

        if (method_exists($treeBuilder, 'getRootNode')) {
            $rootNode = $treeBuilder->getRootNode();
        } else {
            $rootNode = $treeBuilder->root('cache_adapter');
        }

        $rootNode->children()
            ->append($this->getClustersNode())
            ->end();

        return $treeBuilder;
    }
Generates the configuration tree builder.

@return TreeBuilder The tree builder