private function addSessionSection(ArrayNodeDefinition $rootNode)
    {
        $rootNode
            ->children()
                ->arrayNode('session')
                    ->canBeUnset()
                    ->children()
                        ->scalarNode('client')->isRequired()->end()
                        ->scalarNode('prefix')->defaultValue('session')->end()
                        ->scalarNode('ttl')->end()
                        ->booleanNode('locking')->defaultTrue()->end()
                        ->scalarNode('spin_lock_wait')->defaultValue(150000)->end()
                    ->end()
                ->end()
            ->end();
    }