Fix issue with modified backtrace

php allows the backtrace arguments to be modified via the
backtrace. By using array_map we make sure that we do not overwrite
references.

tests/integration/ModifyBackTraceSafeTest.php

@@ -0,0 +1,75 @@
+<?php
+
+declare(strict_types=1);
+
+namespace phpDocumentor\Reflection;
+
+
+use PHPUnit\Framework\TestCase;
+
+/**
+ * @coversNothing
+ */
+class ModifyBackTraceSafeTest extends TestCase
+{
+    public function testBackTraceModificationDoesNotImpactFunctionArguments()
+    {
+        $traverser = new Traverser();
+        $node1 = new Node();
+        $node1->children[] = new Node();
+        $node1->children[] = new Node();
+
+        $traverser->traverse([new Node(), $node1]);
+    }
+}
+
+
+class Node {
+    public $children = [];
+}
+
+class Traverser
+{
+    public function traverse(array $nodes)
+    {
+        $this->traverseArray($nodes);
+    }
+
+    public function traverseArray(array $nodes): array
+    {
+        $doNodes = [];
+
+        foreach ($nodes as &$node) {
+            $node = $this->callback($node);
+            $node = $this->traverseNode($node);
+
+            $doNodes[] = $node;
+        }
+
+        return $doNodes;
+    }
+
+    public function callback(Node $class) : Node
+    {
+        $docblock = <<<DOCBLOCK
+ /**
+  * @see sql.php
+  */
+DOCBLOCK;
+
+        $factor = DocBlockFactory::createInstance();
+
+        $factor->create($docblock);
+
+        return $class;
+    }
+
+    private function traverseNode(Node $node) : Node
+    {
+        if ($node->children) {
+            $this->traverseArray($node->children);
+        }
+
+        return $node;
+    }
+}