OTPHP\ParameterTrait::setSecret PHP Method

    private function setSecret($secret)
    {
        Assertion::nullOrString($secret, 'The secret must be a string or null.');
        if (null === $secret) {
            $secret = trim(Base32::encode(random_bytes(32)), '=');
        }
        $this->parameters['secret'] = $secret;
    }