Register 构造函数$socketName隐式null导致异常问题

GatewayWorker\Register::__construct(): Implicitly marking parameter $socketName as nullable is deprecated, the explicit nullable type must be used instead

// 现有代码采用隐式null导致报错
public function __construct(string $socketName = null, array $contextOption = [])
{
    $this->name = 'Register';
    $this->reloadable = false;
    parent::__construct($socketName, $contextOption);
}

// 修改后代码不会报错
public function __construct(?string $socketName = null, array $contextOption = [])
{
    $this->name = 'Register';
    $this->reloadable = false;
    parent::__construct($socketName, $contextOption);
}