Configuration.php

<?php
namespace Epod4\Moduli\ProtocolloBundle\DependencyInjection;

use Symfony\Component\Config\Definition\Builder\TreeBuilder;
use Symfony\Component\Config\Definition\ConfigurationInterface;

class Configuration implements ConfigurationInterface
{
    public function getConfigTreeBuilder()
    {
        $treeBuilder = new TreeBuilder();
        $rootNode = $treeBuilder->root('epod4_protocollo');

        $rootNode
            ->children()
                ->arrayNode('imap')
                    ->children()
                        ->scalarNode('cartella_ricevute')
                            ->isRequired()
                            ->defaultValue('ricevute')
                            ->info('Nome della cartella IMAP in cui salvare le ricevute')
                        ->end()
                        ->scalarNode('cartella_protocollate')
                            ->isRequired()
                            ->defaultValue('protocollati')
                            ->info('Nome della cartella IMAP in cui salvare le PEC protocollate')
                        ->end()
                        ->scalarNode('cartella_inviate')
                            ->isRequired()
                            ->defaultValue('Inviata')
                            ->info('Nome della cartella IMAP in cui salvare le PEC inviate')
                        ->end()
                    ->end()
                ->end()
            ->end()
        ;

        return $treeBuilder;
    }
}