+                                       ->arrayNode('default')
+                                               ->addDefaultsIfNotSet()
+                                               ->children()
+                                                       ->scalarNode('title')->cannotBeEmpty()->defaultValue($defaults['default']['title'])->end()
+                                                       ->arrayNode('group')
+                                                               ->treatNullLike(array())
+                                                               ->defaultValue($defaults['default']['group'])
+                                                               ->scalarPrototype()->end()
+                                                       ->end()
+                                               ->end()
+                                       ->end()