code: public Double getOperatingSystemMetric(ID metricId) {
          if (PlatformMetricType.OS_SYS_CPU_LOAD.getMetricTypeId().equals(metricId)) {
              return Double.valueOf(getProcessor().getSystemCpuLoad());
          } else if (PlatformMetricType.OS_SYS_LOAD_AVG.getMetricTypeId().equals(metricId)) {
              return Double.valueOf(getProcessor().getSystemLoadAverage());
          } else if (PlatformMetricType.OS_PROCESS_COUNT.getMetricTypeId().equals(metricId)) {
              return Double.valueOf(getOperatingSystem().getProcessCount());
          } else {
              throw new UnsupportedOperationException("Invalid OS metric to collect: " + metricId);
          }
      }
docs: Returns the given OS metric's value.
  
  @param metricId the metric to collect
  @return the value of the metric