code: public static void stop(String name) {
          Long start = PENDING.remove(name);
          if (start == null) {
              return;
          }
          long duration = System.currentTimeMillis() - start;
          Counter sum = CUMULATED.computeIfAbsent(name, k -> new Counter(k, "ms"));
          sum.increment(duration);
      }
docs: Stop the timer identified by the given key. After stopping a timer, the time passed from its
  {@link #start(String) initialization} will be added to the cumulated time of the specific timer.
  
  @param name
  The name of the timer to be stopped.