composer-auto-loader-path.php

<?php

/** @var string */
private static $composerAutoloaderPath = null;

/**
 * @return string
 */
public static function getComposerAutoloaderPath(): string
{
    if (self::$composerAutoloaderPath === null) {
        self::$composerAutoloaderPath = __DIR__ . "/../../../vendor/autoload.php";
    }
    return self::$composerAutoloaderPath;
}

public function onLoad(): void
{
    require_once self::getComposerAutoloaderPath();
}