+                                                       #TODO: see if we can't prevent key normalisation with ->normalizeKeys(false)
+                                                       ->arrayNode('languages')
+                                                               ->treatNullLike([])
+                                                               ->defaultValue($defaults['default']['languages'])
+                                                               ->scalarPrototype()->end()
+                                                       ->end()
+                                                       #TODO: see if we can't prevent key normalisation with ->normalizeKeys(false)
+                                                       ->arrayNode('locales')
+                                                               ->treatNullLike([])
+                                                               ->defaultValue($defaults['default']['locales'])
+                                                               ->scalarPrototype()->end()
+                                                       ->end()