Constructor.
string $key The requested parameter key:
string $sourceId The service id that references the non-existent parameter:
string $sourceKey The parameter key that references the non-existent parameter:
public function __construct($key, $sourceId = null, $sourceKey = null) {
$this->key = $key;
$this->sourceId = $sourceId;
$this->sourceKey = $sourceKey;
$this
->updateRepr();
}