Issue in GetMatchingProductForId, I cannot get which id type's api response.

[arammarm]

When i make request

$upc = ['190021324893', '796201587166', '32323231111', '211212122'];
$product_list = new AmazonProductList( 'store1' );
$product_list->setIdType( "UPC" );
$product_list->setProductIds( $upc );
$product_list->fetchProductList();
$product_list->getProduct();

I don't understand which results is which upc's also i cannot get by order because when wrong upc it's return just response with 'error' array key. when it more than one error it's replace the previous error response. so hard to match the response with upc.