/**
* Meta data system constraint constructor
*
* @param string $constraintType
* @param string $type
* @param string $value
* @param string $minVersion
* @param string $maxVersion
*/
public function __construct($constraintType, $type, $value = null, $minVersion = null, $maxVersion = null)
{
if ($value === '') {
$value = null;
}
parent::__construct($constraintType, $value, $minVersion, $maxVersion);
$this->type = $type;
}