Symfony2 array options config.yml parsing

config.yml

my_root:
    payment_providers:
        - { payment_provider: 'abcd', name: 'Paypal' }
        - { payment_provider: 'xyzt', name: 'Authorize.net' }

Configuration.php

   /**
     * {@inheritDoc}
     */
    public function getConfigTreeBuilder()
    {
        $treeBuilder = new TreeBuilder();
        $rootNode = $treeBuilder->root('my_root');

        $rootNode
            ->children()
                ->arrayNode('payment_providers')
                    ->prototype('array')
                        ->children()
                            ->scalarNode('payment_provider')->end()
                            ->scalarNode('name')->end()
                        ->end()
                    ->end()
                ->end()
            ->end()
        ->end();

        return $treeBuilder;
    }

result:

Array
(
    [payment_providers] => Array
        (
            [0] => Array
                (
                    [payment_provider] => abcd
                    [name] => Paypal
                )

            [1] => Array
                (
                    [payment_provider] => xyzt
                    [name] => Authorize.net
                )

        )

)