code: public static ResourceCalculatorPlugin getResourceCalculatorPlugin(
        Class<? extends ResourceCalculatorPlugin> clazz, Configuration conf) {
  
      if (clazz != null) {
        return ReflectionUtils.newInstance(clazz, conf);
      }
  
      // No class given, try a os specific class
      try {
        String osName = System.getProperty("os.name");
        if (osName.startsWith("Linux")) {
          return new LinuxResourceCalculatorPlugin();
        }
      } catch (SecurityException se) {
        // Failed to get Operating System name.
        return new NullResourceCalculatorPlugin();
      }
  
      // Not supported on this system.
        return new NullResourceCalculatorPlugin();
    }
docs: Get the ResourceCalculatorPlugin from the class name and configure it. If
  class name is null, this method will try and return a memory calculator
  plugin available for this system.
  
  @param clazz class-name
  @param conf configure the plugin with this.
  @return ResourceCalculatorPlugin