message: fix: add hidden tracer attr
diff: @@ -104,7 +104,10 @@ export class Tracer extends OpenTrancer {
  };
  for (let [key, value] of this.attrs.entries()) {
  - result[key] = value.report();
  + const v = value.report();
  + if (v === false) {
  + result[key] = v;
  + }
  }
  return result;
  