Better unsigned numbers management (SCAN-853)

src/main/java/fr/soleil/cdma/box/controller/FileListController.java

@@ -185,6 +185,11 @@ public class FileListController extends AbstractController<File[]> {
         public void clean() {
             decorated = null;
         }
+
+        @Override
+        public boolean isUnsigned() {
+            return false;
+        }
     }
 
 }