[HttpFoundation] Fix type of properties in Request class

Author: nicolas-grekas

Definition/Builder/TreeBuilder.php

@@ -20,7 +20,14 @@
  */
 class TreeBuilder implements NodeParentInterface
 {
+    /**
+     * @var NodeInterface|null
+     */
     protected $tree;
+
+    /**
+     * @var NodeDefinition
+     */
     protected $root;
 
     public function __construct(string $name, string $type = 'array', NodeBuilder $builder = null)
@@ -53,7 +60,7 @@ public function buildTree(): NodeInterface
     public function setPathSeparator(string $separator)
     {
         // unset last built as changing path separator changes all nodes
-        unset($this->tree);
+        $this->tree = null;
 
         $this->root->setPathSeparator($separator);
     }