private DBObject applyFieldFilter(DBObject object) {
   if (object instanceof GridFSFile) {
     GridFSFile file = (GridFSFile) object;
     DBObject metadata = file.getMetaData();
     if (metadata != null) {
       file.setMetaData(applyFieldFilter(metadata));
     }
   } else {
     object = MongoDBHelper.applyExcludeFields(object, definition.getExcludeFields());
     object = MongoDBHelper.applyIncludeFields(object, definition.getIncludeFields());
   }
   return object;
 }