code: public function getConfigTreeBuilder()
      {
          $tb = new TreeBuilder();
          $rootNode = $tb->root('acl');
  
          $rootNode
              ->children()
                  ->scalarNode('connection')
                      ->defaultNull()
                      ->info('any name configured in doctrine.dbal section')
                  ->end()
                  ->arrayNode('cache')
                      ->addDefaultsIfNotSet()
                      ->children()
                          ->scalarNode('id')->end()
                          ->scalarNode('prefix')->defaultValue('sf_acl_')->end()
                      ->end()
                  ->end()
                  ->scalarNode('provider')->end()
                  ->arrayNode('tables')
                      ->addDefaultsIfNotSet()
                      ->children()
                          ->scalarNode('class')->defaultValue('acl_classes')->end()
                          ->scalarNode('entry')->defaultValue('acl_entries')->end()
                          ->scalarNode('object_identity')->defaultValue('acl_object_identities')->end()
                          ->scalarNode('object_identity_ancestors')->defaultValue('acl_object_identity_ancestors')->end()
                          ->scalarNode('security_identity')->defaultValue('acl_security_identities')->end()
                      ->end()
                  ->end()
                  ->arrayNode('voter')
                      ->addDefaultsIfNotSet()
                      ->children()
                          ->booleanNode('allow_if_object_identity_unavailable')->defaultTrue()->end()
                      ->end()
                  ->end()
              ->end()
          ;
  
          return $tb;
      }
docs: Generates the configuration tree builder.
  
  @return TreeBuilder The tree builder