DependencyInjection/Configuration.php
public function getConfigTreeBuilder()
    {
        $treeBuilder = new TreeBuilder();
        $rootNode = $treeBuilder->root('c33s_contact_form');
        
        $rootNode
	    ->children()
		->arrayNode('email')
		    ->canBeEnabled()
		    ->children()
			->scalarNode('subject')
			    ->isRequired()
			    ->cannotBeEmpty()
			->end()
			->scalarNode('sender_email')
			    ->isRequired()
			    ->cannotBeEmpty()
			->end()
			->arrayNode('recipients')
			    ->defaultValue(array())
			    ->useAttributeAsKey('email')
			    ->prototype('scalar')
				->isRequired()
				->cannotBeEmpty()
			    ->end()
			->end()
			->booleanNode('send_copy_to_user')
			    ->defaultValue(false)
			->end()
		    ->end()
		->end()
		->arrayNode('database')
		    ->canBeEnabled()
		->end()
	    ->end()
	;
        
        return $treeBuilder;
    }
public function getConfigTreeBuilder()
    {
        $treeBuilder = new TreeBuilder();
        $rootNode = $treeBuilder->root('c33s_contact_form');
        
        $rootNode
	    ->children()
		->arrayNode('email')
		    ->canBeEnabled()
		    ->children()
			->scalarNode('subject')
			    ->isRequired()
			    ->cannotBeEmpty()
			->end()
			->scalarNode('sender_email')
			    ->isRequired()
			    ->cannotBeEmpty()
			->end()
			->arrayNode('recipients')
			    ->defaultValue(array())
			    ->useAttributeAsKey('email')
			    ->prototype('scalar')
				->isRequired()
				->cannotBeEmpty()
			    ->end()
			->end()
			->booleanNode('send_copy_to_user')
			    ->defaultValue(false)
			->end()
		    ->end()
		->end()
		->arrayNode('database')
		    ->canBeEnabled()
		->end()
	    ->end()
	;
        
        return $treeBuilder;
    }
{@inheritDoc}