magento/magento2#14510: Creating custom customer attribute with default value 0 will cause not saving value for customer entity.

- remove default value for 'links_exist' attribute of Downloadable Product;

Author: al.kravchuk

app/code/Magento/Downloadable/Setup/UpgradeData.php

@@ -0,0 +1,58 @@
+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+
+namespace Magento\Downloadable\Setup;
+
+use Magento\Eav\Setup\EavSetup;
+use Magento\Eav\Setup\EavSetupFactory;
+use Magento\Framework\Setup\ModuleDataSetupInterface;
+use Magento\Framework\Setup\UpgradeDataInterface;
+use Magento\Framework\Setup\ModuleContextInterface;
+
+/**
+ * @codeCoverageIgnore
+ */
+class UpgradeData implements UpgradeDataInterface
+{
+    /**
+     * EAV setup factory
+     *
+     * @var EavSetupFactory
+     */
+    private $eavSetupFactory;
+
+    /**
+     * Init
+     *
+     * @param EavSetupFactory $eavSetupFactory
+     */
+    public function __construct(EavSetupFactory $eavSetupFactory)
+    {
+        $this->eavSetupFactory = $eavSetupFactory;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function upgrade(ModuleDataSetupInterface $setup, ModuleContextInterface $context)
+    {
+        $setup->startSetup();
+
+        if (version_compare($context->getVersion(), '2.0.3', '<')) {
+            /** @var EavSetup $eavSetup */
+            $eavSetup = $this->eavSetupFactory->create(['setup' => $setup]);
+            // remove default value
+            $eavSetup->updateAttribute(
+                \Magento\Catalog\Model\Product::ENTITY,
+                'links_exist',
+                'default_value',
+                null
+            );
+        }
+
+        $setup->endSetup();
+    }
+}

app/code/Magento/Downloadable/etc/module.xml

@@ -6,7 +6,7 @@
  */
 -->
 <config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Module/etc/module.xsd">
-    <module name="Magento_Downloadable" setup_version="2.0.2">
+    <module name="Magento_Downloadable" setup_version="2.0.3">
         <sequence>
             <module name="Magento_Catalog"/>
         </sequence>