Fixes #14370: Fixed creating built-in validator in model with same function name

tests/data/validators/models/ValidatorTestFunctionModel.php

@@ -0,0 +1,20 @@
+<?php
+/**
+ * @link http://www.yiiframework.com/
+ * @copyright Copyright (c) 2008 Yii Software LLC
+ * @license http://www.yiiframework.com/license/
+ */
+
+namespace yiiunit\data\validators\models;
+
+use yii\base\Model;
+
+class ValidatorTestFunctionModel extends Model
+{
+    public $firstAttribute;
+
+    public function required()
+    {
+        return true;
+    }
+}