+ ->arrayNode('facebook')
+ ->addDefaultsIfNotSet()
+ ->children()
+ ->arrayNode('apps')
+ ->treatNullLike([])
+ ->defaultValue($defaults['facebook']['apps'])
+ ->scalarPrototype()->end()
+ ->end()
+ ->integerNode('height')->min(0)->defaultValue($defaults['facebook']['height'])->end()
+ ->integerNode('width')->min(0)->defaultValue($defaults['facebook']['width'])->end()
+ ->end()
+ ->end()