+                                       ->arrayNode('context')
+                                               ->addDefaultsIfNotSet()
+                                               ->children()
+                                                       ->arrayNode('http')
+                                                       ->addDefaultsIfNotSet()
+                                                       ->children()
+                                                               ->scalarNode('max_redirects')->defaultValue($defaults['captcha']['max_redirects'])->end()
+                                                               ->scalarNode('timeout')->defaultValue($defaults['captcha']['timeout'])->end()
+                                                               ->scalarNode('user_agent')->cannotBeEmpty()->defaultValue($defaults['captcha']['user_agent'])->end()
+                                                       ->end()
+                                               ->end()
+                                       ->end()