newsupernova/vendor/magento/module-fedex/etc/di.xml

<?xml version="1.0"?>
<!--
/**
 * Copyright © Magento, Inc. All rights reserved.
 * See COPYING.txt for license details.
 */
-->
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd">
    <type name="Magento\Config\Model\Config\TypePool">
        <arguments>
            <argument name="sensitive" xsi:type="array">
                <item name="carriers/fedex/account" xsi:type="string">1</item>
                <item name="carriers/fedex/key" xsi:type="string">1</item>
                <item name="carriers/fedex/meter_number" xsi:type="string">1</item>
                <item name="carriers/fedex/password" xsi:type="string">1</item>
                <item name="carriers/fedex/production_webservices_url" xsi:type="string">1</item>
                <item name="carriers/fedex/sandbox_webservices_url" xsi:type="string">1</item>
                <item name="carriers/fedex/smartpost_hubid" xsi:type="string">1</item>
            </argument>
            <argument name="environment" xsi:type="array">
                <item name="carriers/fedex/sandbox_mode" xsi:type="string">1</item>
            </argument>
        </arguments>
    </type>
</config>