Update unlink -> is_link

bundle/medona/Controller/ArchiveTransfer.php

@@ -205,7 +205,7 @@ class ArchiveTransfer extends abstractMessage
 
         foreach (scandir($zipFolder) as $file) {
             if ($file != "." && $file != "..") {
-                if (unlink($zipFolder.DIRECTORY_SEPARATOR.$file)) {
+                if (is_link($zipFolder.DIRECTORY_SEPARATOR.$file)) {
                     $this->sendError("202", "The container file contains symbolic links");
                     $exception = \laabs::newException('medona/invalidMessageException', "Invalid message", 400);
                     $exception->errors = $this->errors;