public function getRequestCredentials()
    {
        if ($this->requestCredentials === null) {
            $this->requestCredentials = function () {
                $credentials = [];

                if (isset($_SERVER['PHP_AUTH_USER'])) {
                    $credentials['login'] = $_SERVER['PHP_AUTH_USER'];
                }

                if (isset($_SERVER['PHP_AUTH_PW'])) {
                    $credentials['password'] = $_SERVER['PHP_AUTH_PW'];
                }

                if (count($credentials) > 0) {
                    return $credentials;
                }
            };
        }

        $credentials = $this->requestCredentials;

        return $credentials();
    }