commerce_simplestock-8.x-1.x-dev/commerce_simplestock.module

<?php

/**
 * Implements hook_theme_registry_alter().
 */
function commerce_simplestock_theme_registry_alter(&$theme_registry) {
  $theme_registry['commerce_order__user']['path'] =
    \Drupal::service('extension.list.module')->getPath('commerce_simplestock') . '/templates';
}