TaxRatesAdjustment/bootstrap.php

<?php 

$bootstrapFileName = getenv('ESHOP_BOOTSTRAP_PATH');
if (!empty($bootstrapFileName)) {
    $bootstrapFileName = realpath(trim(getenv('ESHOP_BOOTSTRAP_PATH')));
} else {
    $count = 0;
    $bootstrapFileName = '../../source/bootstrap.php';
    $currentDirectory = __DIR__ . '/';
    while ($count < 5) {
        $count++;
        if (file_exists($currentDirectory . $bootstrapFileName)) {
            $bootstrapFileName = $currentDirectory . $bootstrapFileName;
            break;
        }
        $bootstrapFileName = '../' . $bootstrapFileName;
    }
}

if (!(file_exists($bootstrapFileName) && !is_dir($bootstrapFileName))) {
    $items = [
        "Unable to find eShop bootstrap.php file.",
        "You can override the path by using ESHOP_BOOTSTRAP_PATH environment variable.",
        "\n"
    ];

    $message = implode(" ", $items);

    die($message);
}

require_once($bootstrapFileName);

define('OX_IS_ADMIN', true);

if (false == function_exists('isAdmin')) {
    /**
     * @return bool
     */
    function isAdmin()
    {
        if (defined('OX_IS_ADMIN')) {
            return OX_IS_ADMIN;
        }

        return true;
    }
}