League\Period\Period::getStartDate PHP Method

    public function getStartDate()
    {
        return $this->startDate;
    }

 public function __construct(Season\Name $name, Period $period)
 {
     if ($period === null) {
         throw new \InvalidArgumentException("de periode moet gezet zijn", E_ERROR);
     }
     parent::__construct($period->getStartDate(), $period->getEndDate());
     if ($name === null) {
         throw new \InvalidArgumentException("de naam moet gezet zijn", E_ERROR);
     }
     $this->m_name = $name;
 }