code: public long minRate() {
          long min = (samples.isEmpty() ? 0L : samples.get(0).rate());
          for (Sample s : samples) {
              min = Math.min(min, s.rate());
          }
          return min;
      }
docs: Returns the minimum of the message rates in the SampleGroup.
  
  @return the minimum of the message rates in the SampleGroup