code: public static String stream2taskName(String old) {
          String[] parts = old.split(DELIM);
          if (parts.length >= 7) {
              parts[0] = MetaType.TASK.getV() + parts[0].charAt(1);
              parts[parts.length - 3] = EMPTY;
  
              String metricName = getMergeMetricName(parts[parts.length - 1]);
              parts[parts.length - 1] = metricName;
          }
          return concat(parts);
      }
docs: make streamId empty, remain other parts the same