public function setPrivatization_start_date($privatization_start_date = null)
{
// validation for constraint: string
if (!is_null($privatization_start_date) && !is_string($privatization_start_date)) {
throw new \InvalidArgumentException(sprintf('Invalid value, please provide a string, "%s" given', gettype($privatization_start_date)), __LINE__);
}
$this->privatization_start_date = $privatization_start_date;
return $this;
}