[Config] added append to the node builder

src/Symfony/Component/Config/Definition/Builder/NodeBuilder.php

@@ -124,6 +124,26 @@ class NodeBuilder implements NodeParentInterface
 
         $node = new $class($name);
 
+        $this->append($node);
+
+        return $node;
+    }
+
+    /**
+     * Append a node definition.
+     *
+     *     $node = new ArrayNodeDefinition('name')
+     *         ->children()
+     *             ->scalarNode('foo')
+     *             ->scalarNode('baz')
+     *             ->append($this->getBarNodeDefinition())
+     *         ->end()
+     *     ;
+     *
+     * @return NodeBuilder This node builder
+     */
+    public function append(NodeDefinition $node)
+    {
         if ($node instanceof ParentNodeDefinitionInterface) {
             $builder = clone $this;
             $builder->setParent(null);
@@ -136,7 +156,7 @@ class NodeBuilder implements NodeParentInterface
             $node->setParent($this);
         }
 
-        return $node;
+        return $this;
     }
 
     /**
@@ -144,6 +164,8 @@ class NodeBuilder implements NodeParentInterface
      *
      * @param string $type The name of the type
      * @param string $class The fully qualified name the node definition class
+     *
+     * @return NodeBuilder This node builder
      */
     public function setNodeClass($type, $class)
     {