Wordfence reports Root_Environment.php changed

Dear Support,

version: 2.8.5

Wordfence is reporting the following:

modified plugin file: wp-content/plugins/w3-total-cache/Root_Environment.php

Type: File

This file belongs to plugin “W3 Total Cache” version “2.8.5” and has been modified from the file that is distributed by ww.wp.xz.cn for this version. Please use the link to see how the file has changed. If you have modified this file yourself, you can safely ignore this warning. If you see a lot of changed files in a plugin that have been made by the author, then try uninstalling and reinstalling the plugin to force an upgrade. Doing this is a workaround for plugin authors who don’t manage their code correctly. Learn More

• Orginal file:
• if ( ! empty( $license_key ) ) {  
• Modified File:
• if ( ! emtpy( $license_key ) ) {

Kind Regards,

Rob