code: public static String getTimingStat() {
          final Stopwatch root = STOPWATCH.get();
  
          if (null == root) {
              return "No stopwatch";
          }
  
          final StringBuilder stringBuilder = new StringBuilder();
  
          root.appendTimingStat(1, stringBuilder);
  
          return stringBuilder.toString();
      }
docs: Gets the current timing statistics.
  
  <p>
  If a task is not ended, the outputs will be minus for percentage and elapsed, the absolute value of the elapsed
  filed is the start time.
  </p>
  
  @return the current timing statistics, returns {@code "No stopwatch"} if not stopwatch